feat(streaming): introduce new source executor

[xx01cyx]

I hereby agree to the terms of the Singularity Data, Inc. Contributor License Agreement.

What's changed and what's your intention?

This is the first step of the new DML design.

Summarize your change

Introduce new source executor. It differs from the current one in following ways:

1. The streaming source (SourceExecutorV2.stream_source_core) becomes optional. That is to say, it is possible that a new source executor has no external connector. Under this circumstance, the new source executor's only responsibility is to receive and forward barrier messages.
2. The new source executor will not generate row id for data. This will be done in RowIdGenerateExecutor (to be implemented).

Describe any limitations of the current code

Datagen is used to mock external connector in UT now. A better approach will be introducing a mock connector only for testing. (#6427)

Checklist

• I have written necessary rustdoc comments
• I have added necessary unit tests and integration tests
• All checks passed in ./risedev check (or alias, ./risedev c)

Related Issue

#5949

[github-actions]

license-eye has totally checked 2356 files.

Valid	Invalid	Ignored	Fixed
1139	1	1216	0

Click to see the invalid file list

• src/stream/src/executor/source/source_executor_v2.rs

[codecov]

Codecov Report

Merging #6447 (91ce031) into main (709e1be) will increase coverage by 0.04%.
The diff coverage is 82.89%.

@@            Coverage Diff             @@
##             main    #6447      +/-   ##
==========================================
+ Coverage   73.94%   73.98%   +0.04%     
==========================================
  Files         981      983       +2     
  Lines      159159   160693    +1534     
==========================================
+ Hits       117690   118896    +1206     
- Misses      41469    41797     +328     

Flag	Coverage Δ
rust	73.98% <82.89%> (+0.04%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
src/batch/src/executor/row_seq_scan.rs	20.00% <0.00%> (-0.21%)	⬇️
src/batch/src/lib.rs	100.00% <ø> (ø)
src/frontend/src/handler/variable.rs	0.00% <0.00%> (ø)
...ntend/src/optimizer/plan_node/stream_index_scan.rs	41.40% <0.00%> (-0.33%)	⬇️
src/frontend/src/session.rs	40.36% <0.00%> (ø)
src/source/src/lib.rs	90.00% <ø> (ø)
src/source/src/parser/common.rs	63.63% <ø> (ø)
src/sqlparser/src/keywords.rs	100.00% <ø> (ø)
src/storage/src/hummock/event_handler/mod.rs	0.00% <ø> (ø)
src/storage/src/hummock/local_version/mod.rs	100.00% <ø> (ø)
... and 53 more

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[StrikeW]

Is this PR related to the Unify the materialized source and table RFC?

[xx01cyx]

Is this PR related to the Unify the materialized source and table RFC?

Yes. The tracking issue is here.

[tabVersion]

generally LGTM

[st1page]

LGTM

[mergify]

Hey @xx01cyx, this pull request failed to merge and has been dequeued from the merge train. If you believe your PR failed in the merge train because of a flaky test, requeue it by clicking "Update branch" or pushing an empty commit with git commit --allow-empty -m "rerun" && git push.

[mergify]

Hey @xx01cyx, this pull request failed to merge and has been dequeued from the merge train. If you believe your PR failed in the merge train because of a flaky test, requeue it by clicking "Update branch" or pushing an empty commit with git commit --allow-empty -m "rerun" && git push.