feat: Table Column Groups Table

[NathanZlion]

Description

Add Table Column Grouping Feature support for Table Component.

Related links, issue AWSUI-9594, 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 98.26087% with 8 lines in your changes missing coverage. Please review.
✅ Project coverage is 97.44%. Comparing base (f493264) to head (13e9d0e).

Files with missing lines	Patch %	Lines
src/table/thead.tsx	95.93%	5 Missing ⚠️
src/table/header-cell/group-header-cell.tsx	91.66%	2 Missing ⚠️
src/table/sticky-scrolling.ts	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4482      +/-   ##
==========================================
+ Coverage   97.41%   97.44%   +0.02%     
==========================================
  Files         933      937       +4     
  Lines       29595    29994     +399     
  Branches    10757    10942     +185     
==========================================
+ Hits        28831    29228     +397     
- Misses        716      759      +43     
+ Partials       48        7      -41     

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