Migrate to new labels and add automatic PR labeler

[jedel1043]

Got kinda tired about having to manually assign labels to PRs, so this fixes that.

[github-actions]

Test262 conformance changes

Test result	main count	PR count	difference
Total	52,963	52,963	0
Passed	49,935	49,935	0
Ignored	2,207	2,207	0
Failed	821	821	0
Panics	0	0	0
Conformance	94.28%	94.28%	0.00%

Tested main commit: 50373f1c00129f6d2bb654241185f8e20e10a333
Tested PR commit: 43a2f9865f18390491b70c1156adb6d4f8a6fac4
Compare commits: 50373f1...43a2f98

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 58.89%. Comparing base (6ddc2b4) to head (43a2f98).
⚠️ Report is 906 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #5071       +/-   ##
===========================================
+ Coverage   47.24%   58.89%   +11.64%     
===========================================
  Files         476      563       +87     
  Lines       46892    62572    +15680     
===========================================
+ Hits        22154    36850    +14696     
- Misses      24738    25722      +984     

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