[CHORE] Cleanup ExprResolver

[kevinzwang]

Follow-up from #3399

[kevinzwang]

BTW most of these commits are just from the previous PR

[codspeed-hq]

CodSpeed Performance Report

Merging #3401 will degrade performances by 35.59%

_{Comparing kevin/groupby-key-in-agg (af8b536) with main (68248a9)}

Summary

❌ 3 regressions
✅ 14 untouched benchmarks

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Benchmarks breakdown

	Benchmark	main	kevin/groupby-key-in-agg	Change
❌	test_count[1 Small File]	3.4 ms	3.9 ms	-12.54%
❌	test_iter_rows_first_row[100 Small Files]	236.3 ms	277.4 ms	-14.8%
❌	test_show[100 Small Files]	15.2 ms	23.5 ms	-35.59%

[codecov]

Codecov Report

Attention: Patch coverage is 77.77778% with 4 lines in your changes missing coverage. Please review.

Project coverage is 77.35%. Comparing base (68248a9) to head (af8b536).
Report is 8 commits behind head on main.

Files with missing lines	Patch %	Lines
src/daft-dsl/src/resolve_expr/mod.rs	60.00%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3401      +/-   ##
==========================================
- Coverage   77.35%   77.35%   -0.01%     
==========================================
  Files         685      685              
  Lines       83644    83646       +2     
==========================================
- Hits        64705    64703       -2     
- Misses      18939    18943       +4     

Files with missing lines	Coverage Δ
src/daft-logical-plan/src/ops/agg.rs	58.13% <100.00%> (-1.87%)	⬇️
src/daft-logical-plan/src/ops/pivot.rs	70.58% <100.00%> (-0.85%)	⬇️
src/daft-dsl/src/resolve_expr/mod.rs	88.88% <60.00%> (-1.33%)	⬇️

... and 4 files with indirect coverage changes