feat: Table column groups API II

[NathanZlion]

Description

Related links, issue #, if available: n/a

How has this been tested?

Review checklist

The following items are to be evaluated by the author(s) and the reviewer(s).

Correctness

• Changes include appropriate documentation updates.
• Changes are backward-compatible if not indicated, see CONTRIBUTING.md.
• Changes do not include unsupported browser features, see CONTRIBUTING.md.
• Changes were manually tested for accessibility, see accessibility guidelines.

Security

• If the code handles URLs: all URLs are validated through the checkSafeUrl function.

Testing

• Changes are covered with new/existing unit tests?
• Changes are covered with new/existing integration tests?

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[codecov]

Codecov Report

❌ Patch coverage is 67.01031% with 224 lines in your changes missing coverage. Please review.
✅ Project coverage is 96.68%. Comparing base (d21a76f) to head (d420ae4).
⚠️ Report is 54 commits behind head on main.

Files with missing lines	Patch %	Lines
src/table/use-column-widths.tsx	36.14%	46 Missing and 7 partials ⚠️
src/table/header-cell/group-header-cell.tsx	57.40%	40 Missing and 6 partials ⚠️
...rc/collection-preferences/content-display/utils.ts	30.43%	31 Missing and 1 partial ⚠️
src/table/thead.tsx	73.46%	26 Missing ⚠️
src/table/column-grouping-utils.ts	86.62%	21 Missing ⚠️
...c/collection-preferences/content-display/index.tsx	46.66%	16 Missing ⚠️
...llection-preferences/content-display-preference.ts	23.52%	11 Missing and 2 partials ⚠️
src/table/header-cell/hidden-header-cell.tsx	0.00%	6 Missing ⚠️
src/table/table-role/grid-navigation.tsx	84.61%	3 Missing and 1 partial ⚠️
src/test-utils/dom/table/index.ts	78.57%	3 Missing ⚠️
... and 2 more

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4347      +/-   ##
==========================================
- Coverage   97.42%   96.68%   -0.75%     
==========================================
  Files         893      906      +13     
  Lines       26121    27075     +954     
  Branches     9437     9758     +321     
==========================================
+ Hits        25449    26178     +729     
- Misses        666      837     +171     
- Partials        6       60      +54     

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