feat(log-store): implement a merge stream of kv-log-store

[wenym1]

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What's changed and what's your intention?

During recovery, the kv log store will first process all unconsumed data previously written to storage. It reads the data by iterate over the range (Unbounded, Exclusive(current_epoch)) under each vnode. Since each sink executor handles a set of vnodes, we will have to create multiple iterator corresponding to each vnode and then merge the stream of multiple vnodes. Each stream gets either a row data or a barrier, It will emit an row data if it gets an row data. When getting a barrier, it will wait for all other streams to emit the barrier, and then all streams start to process the data of next epoch. This is similar to barrier aligning.

Checklist For Contributors

• I have written necessary rustdoc comments
• I have added necessary unit tests and integration tests
• I have added fuzzing tests or opened an issue to track them. (Optional, recommended for new SQL features Sqlsmith: Sql feature generation #7934).
• I have demonstrated that backward compatibility is not broken by breaking changes and created issues to track deprecated features to be removed in the future. (Please refer to the issue)
• All checks passed in ./risedev check (or alias, ./risedev c)

Checklist For Reviewers

• I have requested macro/micro-benchmarks as this PR can affect performance substantially, and the results are shown.

Documentation

• My PR DOES NOT contain user-facing changes.

Click here for Documentation

Types of user-facing changes

Please keep the types that apply to your changes, and remove the others.

• Installation and deployment
• Connector (sources & sinks)
• SQL commands, functions, and operators
• RisingWave cluster configuration changes
• Other (please specify in the release note below)

Release note

[codecov]

Codecov Report

Merging #10090 (30efcbd) into main (608e183) will increase coverage by 0.66%.
The diff coverage is 86.37%.

❗ Current head 30efcbd differs from pull request most recent head 712f0cc. Consider uploading reports for the commit 712f0cc to get more accurate results

@@            Coverage Diff             @@
##             main   #10090      +/-   ##
==========================================
+ Coverage   70.44%   71.11%   +0.66%     
==========================================
  Files        1258     1229      -29     
  Lines      214365   210545    -3820     
==========================================
- Hits       151009   149726    -1283     
+ Misses      63356    60819    -2537     

Flag	Coverage Δ
rust	71.11% <86.37%> (+0.66%)	⬆️

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

Impacted Files	Coverage Δ
.../stream/src/common/log_store/kv_log_store/serde.rs	87.84% <86.37%> (-0.83%)	⬇️

... and 452 files with indirect coverage changes

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[st1page]

LGTM

[xx01cyx]

LGTM