Feat rag add more features

[better629]

Features

• rag add engine like es
• rag add rerank like flare, object-rerank-by-field-val, colbert

Feature Docs

Influence

Result

========================================================================================================= test session starts ==========================================================================================================
collected 29 items                                                                                                                                                                                                                     

tests/metagpt/rag/engines/test_simple.py .....                                                                                                                                                                                   [ 17%]
tests/metagpt/rag/factories/test_base.py ..........                                                                                                                                                                              [ 51%]
tests/metagpt/rag/factories/test_ranker.py .....                                                                                                                                                                                 [ 68%]
tests/metagpt/rag/factories/test_retriever.py ......                                                                                                                                                                             [ 89%]
tests/metagpt/rag/retrievers/test_bm25_retriever.py .                                                                                                                                                                            [ 93%]
tests/metagpt/rag/retrievers/test_faiss_retriever.py .                                                                                                                                                                           [ 96%]
tests/metagpt/rag/retrievers/test_hybrid_retriever.py .                                                                                                                                                                          [100%]

=========================================================================================================== warnings summary ===========================================================================================================
=================================================================================================== 29 passed, 7 warnings in 10.90s ====================================================================================================

Other

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 82.69231% with 18 lines in your changes are missing coverage. Please review.

Project coverage is 81.33%. Comparing base (6434503) to head (90e1b62).

Files	Patch %	Lines
metagpt/rag/factories/index.py	43.75%	9 Missing ⚠️
metagpt/rag/factories/retriever.py	57.14%	3 Missing ⚠️
metagpt/rag/rankers/object_ranker.py	90.32%	3 Missing ⚠️
metagpt/rag/factories/ranker.py	71.42%	2 Missing ⚠️
metagpt/rag/retrievers/es_retriever.py	83.33%	1 Missing ⚠️

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Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1114      +/-   ##
==========================================
+ Coverage   81.28%   81.33%   +0.04%     
==========================================
  Files         248      251       +3     
  Lines       13895    13980      +85     
==========================================
+ Hits        11294    11370      +76     
- Misses       2601     2610       +9     

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[geekan]

LGTM