feat(flow): plan def

[discord9]

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Refer to a related PR or issue link

#3187

What's changed and what's your intention?

Added basic plan for dataflow execution, support describe of basic map, reduce and join.

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

• Summarize your change (mandatory)
  Basic Type defination that will be used in future PRs impl actual execution of those plans

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 8.33333% with 11 lines in your changes are missing coverage. Please review.

Project coverage is 84.94%. Comparing base (7639c22) to head (730c185).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3490      +/-   ##
==========================================
- Coverage   85.34%   84.94%   -0.41%     
==========================================
  Files         899      903       +4     
  Lines      149549   149639      +90     
==========================================
- Hits       127639   127106     -533     
- Misses      21910    22533     +623