feat(flow): query table schema&refactor

[discord9]

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Refer to a related PR or issue link (optional)

What's changed and what's your intention?

added TableSource to get table name, id and schema from metasrv, and other minor refactor

Please explain IN DETAIL what the changes are in this PR and why they are needed:

• added TableSource to help flow node get table name, id and schema from metasrv
• refactor SourceSender to allow unbounded broadcast

Checklist

• I have written the necessary rustdoc comments.
• I have added the necessary unit tests and integration tests.
• This PR does not require documentation updates.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 189 lines in your changes are missing coverage. Please review.

Project coverage is 85.39%. Comparing base (15d7b97) to head (a9f16e8).
Report is 2 commits behind head on main.

❗ Current head a9f16e8 differs from pull request most recent head b4708c2. Consider uploading reports for the commit b4708c2 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3943      +/-   ##
==========================================
- Coverage   85.77%   85.39%   -0.38%     
==========================================
  Files         968      970       +2     
  Lines      166463   166614     +151     
==========================================
- Hits       142782   142286     -496     
- Misses      23681    24328     +647     

[zhongzc]

Almost LGTM, very readable PR! 😍

[waynexia]

Others LGTM