Fix some bugs in text2sql.(#4279)(#4281)
### What problem does this PR solve?
- The incorrect results in parsing CSV files of the QA knowledge base in
the text2sql scenario. Process CSV files using the csv library. Decouple
CSV parsing from TXT parsing
- Most llm return results in markdown format ```sql query ```, Fix
execution error caused by LLM output SQLmarkdown format.### Type of
change
- [x] Bug Fix (non-breaking change which fixes an issue)
dd13a5d05c