feat: Add support for multimodal embeddings in vectorizers (#452)

This PR generalizes the `BaseVectorizer` to be agnostic to any modality
(since it previously exclusively supported text inputs). Building from
the new base, this PR then extends the implementation for some
vectorizers to support multimodal embeddings (renaming them away from
being specifically for text).

## `BaseVectorizer`

The move away from having the `BaseVectorizer` explicitly expect text
inputs means a change in the signature of the `embed` methods away from
`vectorizer.embed(text="lorem ipsum...")` to
`vectorizer.embed(content="lorem ipsum...")`. This is a breaking change
for existing usages of the vectorizers that use the keyword argument,
and the usages will need to be updated to align with the new schema.

Caching for multimodal embeddings is supported for all vectorizers
introduced in this PR.

## Multimodal Implementations

The following vectorizers have been renamed to no longer be explicitly
text vectorizers, and moved to no longer be defined in the
`vectorize.text` module. Imports and usages for these vectorizers will
need to be updated to avoid errors. The `CustomTextVectorizer` has also
been renamed and moved to be
`redisvl.utils.vectorize.custom.CustomVectorizer`.

### VoyageAI

Old: `redisvl.utils.vectorize.text.voyageai.VoyageAITextVectorizer`
New: `redisvl.utils.vectorize.voyageai.VoyageAIVectorizer`

```python
from redisvl.utils.vectorize import VoyageAIVectorizer

# --- Basic usage
vectorizer = VoyageAIVectorizer(
    model="voyage-3-large",
    api_config={"api_key": "your-voyageai-api-key"} # OR set VOYAGE_API_KEY in your env
)
query_embedding = vectorizer.embed(
    content="your input query text here",
    input_type="query"
)
doc_embeddings = vectorizer.embed_many(
    contents=["your document text", "more document text"],
    input_type="document"
)

# --- Multimodal usage - requires Pillow and voyageai>=0.3.6 (for video)
from PIL import Image
from voyageai.video_utils import Video

vectorizer = VoyageAIVectorizer(
    model="voyage-multimodal-3.5",
    api_config={"api_key": "your-voyageai-api-key"} # OR set VOYAGE_API_KEY in your env
)

# text
text_embedding = vectorizer.embed(
    content="your input query text here",
    input_type="query"
)

# image
image_embedding = vectorizer.embed_image(
    "path/to/your/image.jpg",
    input_type="query"
)
image_embedding = vectorizer.embed(
    Image.open("path/to/your/image.jpg"),
    input_type="query"

# video
video_embedding = vectorizer.embed_video(
    "path/to/your/video.mp4",
    input_type="document"
)
video_embedding = vectorizer.embed(
    Video.from_path("path/to/your/video.mp4", model=vectorizer.model),
    input_type="document"
)
```

### Vertex AI

Old: `redisvl.utils.vectorize.text.vertexai.VertexAITextVectorizer`
New: `redisvl.utils.vectorize.vertexai.VertexAIVectorizer`

```python
from redisvl.utils.vectorize import VertexAIVectorizer

# Basic usage

vectorizer = VertexAIVectorizer(
    model="textembedding-gecko",
    api_config={
        "project_id": "your_gcp_project_id", # OR set GCP_PROJECT_ID
        "location": "your_gcp_location",     # OR set GCP_LOCATION
    })
embedding = vectorizer.embed("Hello, world!")

# Multimodal usage
from vertexai.vision_models import Image, Video

vectorizer = VertexAIVectorizer(
    model="multimodalembedding@001",
    api_config={
        "project_id": "your_gcp_project_id", # OR set GCP_PROJECT_ID
        "location": "your_gcp_location",     # OR set GCP_LOCATION
    }
)
text_embedding = vectorizer.embed("Hello, world!")

image_embedding = vectorizer.embed(Image.load_from_file("path/to/your/image.jpg"))
image_embedding = vectorizer.embed_image("path/to/your/image.jpg")

video_embedding = vectorizer.embed(Video.load_from_file("path/to/your/video.mp4"))
video_embedding = vectorizer.embed_video("path/to/your/video.mp4")
```

### Amazon Bedrock

Old: `redisvl.utils.vectorize.text.bedrock.BedrockTextVectorizer`
New: `redisvl.utils.vectorize.bedrock.BedrockVectorizer`

```python
from redisvl.utils.vectorize import BedrockVectorizer

vectorizer = BedrockVectorizer(
    model="amazon.titan-embed-text-v2:0",
    api_config={
        "aws_access_key_id": "your_access_key",
        "aws_secret_access_key": "your_secret_key",
        "aws_region": "us-east-1"
    }
)

embedding = vectorizer.embed("Hello, world!")

# Multimodal usage
from pathlib import Path
from PIL import Image

vectorizer = BedrockVectorizer(
    model="amazon.titan-embed-image-v1:0",
    api_config={
        "aws_access_key_id": "your_access_key",
        "aws_secret_access_key": "your_secret_key",
        "aws_region": "us-east-1"
    }
)
image_embedding = vectorizer.embed(Path("path/to/your/image.jpg"))
image_embedding = vectorizer.embed(Image.open("path/to/other/image.png"))
image_embedding = vectorizer.embed_image("path/to/your/image.jpg")

# Embedding a list of mixed modalities
embeddings = vectorizer.embed_many(
    ["Hello", "world!", Path("path/to/your/image.jpg"), Image.open("path/to/other/image.png")],
    batch_size=2
)
```

### Hugging Face

While the sentence-transformers package does not explicitly allow for
multimodal usage (the package is designed for text-based use-cases),
some officially supported multimodal models can be used without issue
via the `SentenceTransformer` class. This PR removes strict enforcement
of text inputs for the `HFTextVectorizer` to enable these use-cases.

```python
from PIL import Image
from redisvl.utils.vectorize import HFTextVectorizer

vectorizer = HFTextVectorizer(model="sentence-transformers/clip-ViT-L-14")
embeddings1 = vectorizer.embed("Hello, world!")
embeddings2 = vectorizer.embed(Image.open("path/to/your/image.jpg"))
```

## Open Topics

Since this PR introduces a few breaking changes, do we want to maintain
backwards compatibility (with deprecation warnings) for syntax that is
changing? This includes:
- `vectorizer.embed(text=...)` -> `vectorizer.embed(content=...)`
- `VoyageAITextVectorizer` -> `VoyageAIVectorizer`
- `VertexAITextVectorizer` -> `VertexAIVectorizer`
- `BedrockTextVectorizer` -> `BedrockVectorizer`
- `CustomTextVectorizer` -> `CustomVectorizer`

Author: vishal-bala

docs/api/vectorizer.rst

@@ -2,6 +2,19 @@
 Vectorizers
 ***********
 
+.. note::
+   **Backwards Compatibility:** Several vectorizers have deprecated aliases
+   available in the ``redisvl.utils.vectorize.text`` module for backwards
+   compatibility:
+
+   - ``VoyageAITextVectorizer`` → Use ``VoyageAIVectorizer`` instead
+   - ``VertexAITextVectorizer`` → Use ``VertexAIVectorizer`` instead
+   - ``BedrockTextVectorizer`` → Use ``BedrockVectorizer`` instead
+   - ``CustomTextVectorizer`` → Use ``CustomVectorizer`` instead
+
+   These aliases are deprecated as of version 0.13.0 and will be removed
+   in a future major release.
+
 HFTextVectorizer
 ================
 
@@ -38,14 +51,19 @@ AzureOpenAITextVectorizer
    :members:
 
 
-VertexAITextVectorizer
+VertexAIVectorizer
 ======================
 
-.. _vertexaitextvectorizer_api:
+.. _vertexaivectorizer_api:
+
+.. currentmodule:: redisvl.utils.vectorize.vertexai
 
-.. currentmodule:: redisvl.utils.vectorize.text.vertexai
+.. note::
+    For backwards compatibility, an alias ``VertexAITextVectorizer`` is available
+    in the ``redisvl.utils.vectorize.text`` module. This alias is deprecated
+    as of version 0.13.0 and will be removed in a future major release.
 
-.. autoclass:: VertexAITextVectorizer
+.. autoclass:: VertexAIVectorizer
    :show-inheritance:
    :members:
 
@@ -62,37 +80,64 @@ CohereTextVectorizer
    :members:
 
 
-BedrockTextVectorizer
+BedrockVectorizer
 =====================
 
-.. _bedrocktextvectorizer_api:
+.. _bedrockvectorizer_api:
 
-.. currentmodule:: redisvl.utils.vectorize.text.bedrock
+.. currentmodule:: redisvl.utils.vectorize.bedrock
 
-.. autoclass:: BedrockTextVectorizer
+.. note::
+    For backwards compatibility, an alias ``BedrockTextVectorizer`` is available
+    in the ``redisvl.utils.vectorize.text`` module. This alias is deprecated
+    as of version 0.13.0 and will be removed in a future major release.
+
+.. autoclass:: BedrockVectorizer
    :show-inheritance:
    :members:
 
 
-CustomTextVectorizer
+CustomVectorizer
 ====================
 
-.. _customtextvectorizer_api:
+.. _customvectorizer_api:
+
+.. currentmodule:: redisvl.utils.vectorize.custom
 
-.. currentmodule:: redisvl.utils.vectorize.text.custom
+.. note::
+    For backwards compatibility, an alias ``CustomTextVectorizer`` is available
+    in the ``redisvl.utils.vectorize.text`` module. This alias is deprecated
+    as of version 0.13.0 and will be removed in a future major release.
 
-.. autoclass:: CustomTextVectorizer
+.. autoclass:: CustomVectorizer
    :show-inheritance:
    :members:
 
 
-VoyageAITextVectorizer
+VoyageAIVectorizer
 ======================
 
-.. _voyageaitextvectorizer_api:
+.. _voyageaivectorizer_api:
+
+.. currentmodule:: redisvl.utils.vectorize.voyageai
+
+.. note::
+    For backwards compatibility, an alias ``VoyageAITextVectorizer`` is available
+    in the ``redisvl.utils.vectorize.text`` module. This alias is deprecated
+    as of version 0.13.0 and will be removed in a future major release.
+
+.. autoclass:: VoyageAIVectorizer
+   :show-inheritance:
+   :members:
+
+
+MistralAITextVectorizer
+========================
+
+.. _mistralaitextvectorizer_api:
 
-.. currentmodule:: redisvl.utils.vectorize.text.voyageai
+.. currentmodule:: redisvl.utils.vectorize.text.mistral
 
-.. autoclass:: VoyageAITextVectorizer
+.. autoclass:: MistralAITextVectorizer
    :show-inheritance:
    :members: