refactor(plan_node): ProjectSet and Project nodes

[ice1000]

I hereby agree to the terms of the RisingWave Labs, Inc. Contributor License Agreement.

What's changed and what's your intention?

Follow up of #8898, #8870, #8905, #8930, #8932, #9011, #9044, #9176, #9209, #9288, #9290.

Checklist For Contributors

• Yes

Documentation

• My PR DOES NOT contain user-facing changes.

[codecov]

Codecov Report

Merging #9304 (4f8917b) into main (e7521ac) will decrease coverage by 0.02%.
The diff coverage is 96.11%.

@@            Coverage Diff             @@
##             main    #9304      +/-   ##
==========================================
- Coverage   70.81%   70.80%   -0.02%     
==========================================
  Files        1219     1219              
  Lines      202493   202469      -24     
==========================================
- Hits       143405   143361      -44     
- Misses      59088    59108      +20     

Flag	Coverage Δ
rust	70.80% <96.11%> (-0.02%)	⬇️

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

Impacted Files	Coverage Δ
...frontend/src/optimizer/plan_node/logical_source.rs	70.67% <50.00%> (ø)
...ntend/src/optimizer/plan_node/batch_project_set.rs	70.00% <91.66%> (-2.73%)	⬇️
.../frontend/src/optimizer/plan_node/batch_project.rs	81.48% <93.33%> (-1.28%)	⬇️
...tend/src/optimizer/plan_node/stream_project_set.rs	75.00% <93.33%> (-3.69%)	⬇️
src/frontend/src/optimizer/mod.rs	92.39% <100.00%> (ø)
...end/src/optimizer/plan_node/generic/project_set.rs	100.00% <100.00%> (ø)
...rc/frontend/src/optimizer/plan_node/logical_agg.rs	95.73% <100.00%> (ø)
...c/frontend/src/optimizer/plan_node/logical_join.rs	89.60% <100.00%> (ø)
...rontend/src/optimizer/plan_node/logical_project.rs	93.49% <100.00%> (-4.44%)	⬇️
...end/src/optimizer/plan_node/logical_project_set.rs	94.98% <100.00%> (-2.44%)	⬇️
... and 5 more

... and 3 files with indirect coverage changes

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