Add text chunking functionality to chat endpoint

- Introduced SentenceTextChunker and SentenceTextChunkerConfig for improved text processing in chat responses.
- Updated chat endpoint to conditionally use text chunking based on the new 'useTextChunk' parameter from the request.
- Enhanced logging to include 'useTextChunk' status and adjusted text delta handling to support chunked responses.
- Modified ProcessRequest_chat model to include 'useTextChunk' field for request handling.
- Added unit tests for SentenceTextChunker to ensure correct chunking behavior and edge case handling.

src/schemas/models.py

@@ -6,6 +6,7 @@ class ProcessRequest_chat(BaseModel):
     timeStamp: str = Field(..., max_length=32)
     text: str = Field(...)
     needFormUpdate: bool = False
+    useTextChunk: bool = False
 
 class ProcessResponse_chat(BaseModel):
     sessionId: str = Field(..., max_length=64)