Change modeling of project lists in logical plan

[alancai98]

Changes the modeling of partiql-logical's project to be a Vec rather than a HashMap. Previously, couldn't include multiple project aliases with the same name.

For some context, some conformance tests that will be fixed in an upcoming PR are partially failing because the select list included multiple expressions with the same alias.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[codecov]

Codecov Report

Patch coverage: 100.00% and project coverage change: -0.01% ⚠️

Comparison is base (a43f057) 81.41% compared to head (c665bfc) 81.40%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #415      +/-   ##
==========================================
- Coverage   81.41%   81.40%   -0.01%     
==========================================
  Files          53       53              
  Lines       14914    14909       -5     
  Branches    14914    14909       -5     
==========================================
- Hits        12142    12137       -5     
  Misses       2251     2251              
  Partials      521      521              

Files Changed	Coverage Δ
partiql-logical/src/lib.rs	40.46% <ø> (ø)
partiql-eval/src/eval/evaluable.rs	89.46% <100.00%> (ø)
partiql-eval/src/lib.rs	98.69% <100.00%> (ø)
partiql-eval/src/plan.rs	92.61% <100.00%> (ø)
partiql-logical-planner/src/lower.rs	85.73% <100.00%> (-0.06%)	⬇️

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[github-actions]

Conformance comparison report

	Base (a43f057)	257daa1	+/-
% Passing	85.99%	85.99%	0.00%
✅ Passing	5436	5436	0
❌ Failing	886	886	0
🔶 Ignored	0	0	0
Total Tests	6322	6322	0

Number passing in both: 5436

Number failing in both: 886

Number passing in Base (a43f057) but now fail: 0

Number failing in Base (a43f057) but now pass: 0

[alancai98]

This was the conformance test that referenced multiple SELECT items that have the same alias: https://github.com/partiql/partiql-tests/blob/main/partiql-tests-data/eval/query/select/select-mysql.ion#L13776. This PR along with the fix for variable resolution in #410 will fix that test.