feat: allow returning embeddings and metadata from /vector_stores/ methods; disallow changing Provider ID (#4046)

# What does this PR do?

- Updates `/vector_stores/{vector_store_id}/files/{file_id}/content` to
allow returning `embeddings` and `metadata` using the `extra_query`
    -  Updates the UI accordingly to display them.

- Update UI to support CRUD operations in the Vector Stores section and
adds a new modal exposing the functionality.

- Updates Vector Store update to fail if a user tries to update Provider
ID (which doesn't make sense to allow)

```python
In  [1]: client.vector_stores.files.content(
    vector_store_id=vector_store.id, 
    file_id=file.id, 
    extra_query={"include_embeddings": True, "include_metadata": True}
)
Out [1]: FileContentResponse(attributes={}, content=[Content(text='This is a test document to check if embeddings are generated properly.\n', type='text', embedding=[0.33760684728622437, ...,], chunk_metadata={'chunk_id': '62a63ae0-c202-f060-1b86-0a688995b8d3', 'document_id': 'file-27291dbc679642ac94ffac6d2810c339', 'source': None, 'created_timestamp': 1762053437, 'updated_timestamp': 1762053437, 'chunk_window': '0-13', 'chunk_tokenizer': 'DEFAULT_TIKTOKEN_TOKENIZER', 'chunk_embedding_model': 'sentence-transformers/nomic
-ai/nomic-embed-text-v1.5', 'chunk_embedding_dimension': 768, 'content_token_count': 13, 'metadata_token_count': 9}, metadata={'filename': 'test-embedding.txt', 'chunk_id': '62a63ae0-c202-f060-1b86-0a688995b8d3', 'document_id': 'file-27291dbc679642ac94ffac6d2810c339', 'token_count': 13, 'metadata_token_count': 9})], file_id='file-27291dbc679642ac94ffac6d2810c339', filename='test-embedding.txt')
```

Screenshots of UI are displayed below:

### List Vector Store with Added "Create New Vector Store"
<img width="1912" height="491" alt="Screenshot 2025-11-06 at 10 47
25 PM"
src="https://github.com/user-attachments/assets/a3a3ddd9-758d-4005-ac9c-5047f03916f3"
/>

### Create New Vector Store
<img width="1918" height="1048" alt="Screenshot 2025-11-06 at 10 47
49 PM"
src="https://github.com/user-attachments/assets/b4dc0d31-696f-4e68-b109-27915090f158"
/>

### Edit Vector Store
<img width="1916" height="1355" alt="Screenshot 2025-11-06 at 10 48
32 PM"
src="https://github.com/user-attachments/assets/ec879c63-4cf7-489f-bb1e-57ccc7931414"
/>


### Vector Store Files Contents page (with Embeddings)
<img width="1914" height="849" alt="Screenshot 2025-11-06 at 11 54
32 PM"
src="https://github.com/user-attachments/assets/3095520d-0e90-41f7-83bd-652f6c3fbf27"
/>

### Vector Store Files Contents Details page (with Embeddings)
<img width="1916" height="1221" alt="Screenshot 2025-11-06 at 11 55
00 PM"
src="https://github.com/user-attachments/assets/e71dbdc5-5b49-472b-a43a-5785f58d196c"
/>

<!-- If resolving an issue, uncomment and update the line below -->
<!-- Closes #[issue-number] -->

## Test Plan
Tests added for Middleware extension and Provider failures.

---------

Signed-off-by: Francisco Javier Arceo <farceo@redhat.com>

tests/unit/core/routers/test_vector_io.py

@@ -55,3 +55,65 @@ async def test_create_vector_stores_multiple_providers_missing_provider_id_error
 
     with pytest.raises(ValueError, match="Multiple vector_io providers available"):
         await router.openai_create_vector_store(request)
+
+
+async def test_update_vector_store_provider_id_change_fails():
+    """Test that updating a vector store with a different provider_id fails with clear error."""
+    mock_routing_table = Mock()
+
+    # Mock an existing vector store with provider_id "faiss"
+    mock_existing_store = Mock()
+    mock_existing_store.provider_id = "inline::faiss"
+    mock_existing_store.identifier = "vs_123"
+
+    mock_routing_table.get_object_by_identifier = AsyncMock(return_value=mock_existing_store)
+    mock_routing_table.get_provider_impl = AsyncMock(
+        return_value=Mock(openai_update_vector_store=AsyncMock(return_value=Mock(id="vs_123")))
+    )
+
+    router = VectorIORouter(mock_routing_table)
+
+    # Try to update with different provider_id in metadata - this should fail
+    with pytest.raises(ValueError, match="provider_id cannot be changed after vector store creation"):
+        await router.openai_update_vector_store(
+            vector_store_id="vs_123",
+            name="updated_name",
+            metadata={"provider_id": "inline::sqlite"},  # Different provider_id
+        )
+
+    # Verify the existing store was looked up to check provider_id
+    mock_routing_table.get_object_by_identifier.assert_called_once_with("vector_store", "vs_123")
+
+    # Provider should not be called since validation failed
+    mock_routing_table.get_provider_impl.assert_not_called()
+
+
+async def test_update_vector_store_same_provider_id_succeeds():
+    """Test that updating a vector store with the same provider_id succeeds."""
+    mock_routing_table = Mock()
+
+    # Mock an existing vector store with provider_id "faiss"
+    mock_existing_store = Mock()
+    mock_existing_store.provider_id = "inline::faiss"
+    mock_existing_store.identifier = "vs_123"
+
+    mock_routing_table.get_object_by_identifier = AsyncMock(return_value=mock_existing_store)
+    mock_routing_table.get_provider_impl = AsyncMock(
+        return_value=Mock(openai_update_vector_store=AsyncMock(return_value=Mock(id="vs_123")))
+    )
+
+    router = VectorIORouter(mock_routing_table)
+
+    # Update with same provider_id should succeed
+    await router.openai_update_vector_store(
+        vector_store_id="vs_123",
+        name="updated_name",
+        metadata={"provider_id": "inline::faiss"},  # Same provider_id
+    )
+
+    # Verify the provider update method was called
+    mock_routing_table.get_provider_impl.assert_called_once_with("vs_123")
+    provider = await mock_routing_table.get_provider_impl("vs_123")
+    provider.openai_update_vector_store.assert_called_once_with(
+        vector_store_id="vs_123", name="updated_name", expires_after=None, metadata={"provider_id": "inline::faiss"}
+    )