feat(pwmj): support RightSemi/RightAnti existence joins

[SubhamSinghal]

Which issue does this PR close?

Part of #17427 (the PiecewiseMergeJoin epic). This is the second half of its existence-join item: #23870 added LeftSemi/LeftAnti, this adds RightSemi/RightAnti. Only the Mark joins remain unsupported.

Rationale for this change

A range-predicate right semi/anti join — ... RIGHT SEMI JOIN r ON l.v > r.v, or any query that decorrelates to one — currently falls back to NestedLoopJoinExec.

What changes are included in this PR?

New RightExistencePWMJStream (right_existence_join.rs), a 3-state machine: await the buffered reduction, then per streamed batch evaluate the key, compare it against the reduced key with a vectorized cmp kernel, and filter. Plus:

• exec.rs — dispatch; build_buffered_extreme, which folds every buffered partition on its own SpawnedTask; BufferedExtreme as the shared state; relaxed ordering, distribution and partitioning declarations for these two join types; removal of the dead sort_options flip and the unimplemented!() placeholder that the swap design had left behind.
• physical_planner.rs — the gate now excludes only the Mark joins.
• utils.rs — is_supported_existence_join widened; new is_supported_right_existence_join (which deliberately excludes RightMark, so a Mark join cannot inherit the relaxed input requirements if that gate is ever loosened); no visited-indices bitmap allocated for these join types.
• extreme_key made pub(super) so both existence streams share one implementation.

Are these changes tested?

Yes

Benchmark

Microbenchmark, 20K × 20K rows, single inequality, enable_piecewise_merge_join on vs off

Case	PWMJ	NestedLoopJoin	Speedup
RightSemi, all match	~0.023 ms	~77 ms	~3,300×
RightAnti, all match	~0.024 ms	~77 ms	~3,200×
RightSemi, no match	~0.023 ms	~78 ms	~3,300×
RightAnti, no match	~0.024 ms	~78 ms	~3,300×
RightSemi, half match	~0.036 ms	~78 ms	~2,200×
RightAnti, half match	~0.036 ms	~77 ms	~2,100×

Are there any user-facing changes?

No

[SubhamSinghal]

benchmark PR: #24458

[codecov-commenter]

Codecov Report

❌ Patch coverage is 87.98220% with 81 lines in your changes missing coverage. Please review.
✅ Project coverage is 81.26%. Comparing base (bb038a6) to head (5116d05).
⚠️ Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
...joins/piecewise_merge_join/right_existence_join.rs	88.08%	20 Missing and 36 partials ⚠️
...ysical-plan/src/joins/piecewise_merge_join/exec.rs	86.97%	6 Missing and 19 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #24457      +/-   ##
==========================================
+ Coverage   81.23%   81.26%   +0.03%     
==========================================
  Files        1112     1113       +1     
  Lines      390635   392183    +1548     
  Branches   390635   392183    +1548     
==========================================
+ Hits       317350   318727    +1377     
- Misses      54650    54695      +45     
- Partials    18635    18761     +126     

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[SubhamSinghal]

@comphead @kumarUjjawal PR for right semi/anti join. Please help in reviewing this PR. Thanks.

[comphead]

Thanks @SubhamSinghal I'll check this today