feat(service): add multimodal embedder

[tpoisonooo]

1. Remove langchain, re-implement Query, Splitter, Faiss and Chunk

• Thus we can add progress bar when build feature store, then we know how many time left
  

• And easily support multimodal retrieval

  For text-only gradio demo

  

  For multimodal gradio demo

  

2. merge db-reject and db-response, simplify implementation
3. simplify requirements.txt

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add more example: