Merge fixes from dev-ion-doc feature branch back to main

[jpschorr]

Merge behavior-preserving fixes/cleanup/upgrades from dev-ion-doc branch to main

All commits have already been PRed; this is just merging them back into main.

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

[codecov]

Codecov Report

Attention: Patch coverage is 96.98276% with 21 lines in your changes missing coverage. Please review.

Project coverage is 80.49%. Comparing base (deff7a8) to head (7a8a028).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
partiql-parser/src/lexer/mod.rs	96.77%	0 Missing and 12 partials ⚠️
partiql-parser/src/lexer/partiql.rs	96.77%	4 Missing ⚠️
partiql-parser/src/lexer/comment.rs	96.55%	2 Missing ⚠️
partiql-parser/src/lexer/embedded_ion.rs	96.36%	2 Missing ⚠️
extension/partiql-extension-ion/src/lib.rs	98.76%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #497      +/-   ##
==========================================
- Coverage   80.54%   80.49%   -0.06%     
==========================================
  Files          70       73       +3     
  Lines       19040    18947      -93     
  Branches    19040    18947      -93     
==========================================
- Hits        15336    15251      -85     
- Misses       3257     3271      +14     
+ Partials      447      425      -22     

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[github-actions]

Conformance comparison report

	Base (deff7a8)	8098cea	+/-
% Passing	90.35%	90.35%	0.00%
✅ Passing	5731	5731	0
❌ Failing	612	612	0
🔶 Ignored	0	0	0
Total Tests	6343	6343	0

Number passing in both: 5731

Number failing in both: 612

Number passing in Base (deff7a8) but now fail: 0

Number failing in Base (deff7a8) but now pass: 0