Add System.Diagnostics.DiagnosticSource version

[JeremyKuhne]

Useful for .NET Framework polyfill. Tweak System.Runtime.CompilerServices.Unsafe to a newer released version.

Add files to solution folder for convenience.

Microsoft Reviewers: Open in CodeFlow

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 77.31280%. Comparing base (d7b99bf) to head (6b7c7a3).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@                 Coverage Diff                 @@
##                main      #14358         +/-   ##
===================================================
- Coverage   77.31388%   77.31280%   -0.00109%     
===================================================
  Files           3265        3265                 
  Lines         644447      644447                 
  Branches       47631       47631                 
===================================================
- Hits          498247      498240          -7     
- Misses        142511      142517          +6     
- Partials        3689        3690          +1     

Flag	Coverage Δ
Debug	77.31280% <ø> (-0.00109%)	⬇️
integration	19.13020% <ø> (-0.00244%)	⬇️
production	52.27805% <ø> (-0.00244%)	⬇️
test	97.41916% <ø> (ø)
unit	49.63629% <ø> (+0.00243%)	⬆️

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