[repo] Auto label pull requests

[CodeBlanch]

Changes

• Improves the add-labels.yml workflow to also label PRs based on the files being changed.
• Switches release automation to use the release label (new) instead of infra and use [release] prefix in PR titles instead of [repo].

Merge requirement checklist

• CONTRIBUTING guidelines followed (license requirements, nullable enabled, static analysis, etc.)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 86.14%. Comparing base (6250307) to head (004efcf).
Report is 254 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5681      +/-   ##
==========================================
+ Coverage   83.38%   86.14%   +2.75%     
==========================================
  Files         297      254      -43     
  Lines       12531    11054    -1477     
==========================================
- Hits        10449     9522     -927     
+ Misses       2082     1532     -550     

Flag	Coverage Δ
unittests	?
unittests-Project-Experimental	86.02% <ø> (?)
unittests-Project-Stable	86.06% <ø> (?)
unittests-Solution	86.04% <ø> (?)
unittests-UnstableCoreLibraries-Experimental	20.12% <ø> (?)

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see 126 files with indirect coverage changes