[multistage] Refactor all StageNodes to PlanNodes during query planning phase

[xiangfu0]

This PR hasn't introduced any logical changes, only renaming.

1. Renames the interface StageNode to PlanNode.
2. Renames all the StageNode implementations to corresponding PlanNode implementations
3. Since we separated the working of stage in query planner phase as planFragment, we also change all the stageId -> planFragmentId and rename all the stage related wording in planner to planFragment

[codecov-commenter]

Codecov Report

Merging #10735 (889eff0) into master (6c62784) will decrease coverage by 7.16%.
The diff coverage is 74.28%.

@@             Coverage Diff              @@
##             master   #10735      +/-   ##
============================================
- Coverage     70.35%   63.19%   -7.16%     
+ Complexity     6462     5238    -1224     
============================================
  Files          2124     2108      -16     
  Lines        114340   113913     -427     
  Branches      17254    17199      -55     
============================================
- Hits          80440    71985    -8455     
- Misses        28288    36672    +8384     
+ Partials       5612     5256     -356     

Flag	Coverage Δ
integration1	24.36% <0.00%> (+0.05%)	⬆️
integration2	23.84% <0.00%> (-0.08%)	⬇️
unittests1	67.87% <74.28%> (+<0.01%)	⬆️
unittests2	?

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

Impacted Files	Coverage Δ
...not/query/planner/logical/RelToStageConverter.java	93.68% <ø> (ø)
...t/query/planner/logical/ShuffleRewriteVisitor.java	0.00% <ø> (ø)
...uery/planner/physical/DispatchablePlanContext.java	100.00% <ø> (ø)
...ery/planner/physical/DispatchablePlanMetadata.java	84.37% <0.00%> (ø)
...hysical/colocated/GreedyShuffleRewriteContext.java	0.00% <0.00%> (ø)
...located/GreedyShuffleRewritePreComputeVisitor.java	0.00% <0.00%> (ø)
...hysical/colocated/GreedyShuffleRewriteVisitor.java	0.00% <0.00%> (ø)
...che/pinot/query/planner/plannode/ExchangeNode.java	83.33% <0.00%> (ø)
...pinot/query/runtime/operator/HashJoinOperator.java	94.16% <ø> (ø)
...uery/runtime/operator/WindowAggregateOperator.java	95.28% <ø> (ø)
... and 34 more

... and 302 files with indirect coverage changes

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more