Migrate to Microsoft.IdentityModel.JsonWebTokens

[iamcarbon]

This PR:

• Enables C#12
• Updates the library to use the modernized Microsoft.IdentityModel.JsonWebTokens library
• Updates the demos to use .net8.0 (the main library continues to target net6.0)
• Fixes various dotnet format violations
• Updates xunit to the latest version
• Updates System.Formats.Cbor to 8.0.0
• Replaces DataHelper.Concat with collection expressions

[codecov-commenter]

Codecov Report

Attention: 20 lines in your changes are missing coverage. Please review.

Comparison is base (5284757) 74.11% compared to head (a7144c0) 73.88%.

Files	Patch %	Lines
...c/Fido2/Metadata/Fido2MetadataServiceRepository.cs	0.00%	12 Missing ⚠️
...ido2/Objects/DevicePublicKeyAuthenticatorOutput.cs	0.00%	6 Missing ⚠️
Src/Fido2/AuthenticatorAssertionResponse.cs	50.00%	1 Missing ⚠️
Src/Fido2/AuthenticatorAttestationResponse.cs	0.00%	1 Missing ⚠️

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Additional details and impacted files

@@            Coverage Diff             @@
##           master     #476      +/-   ##
==========================================
- Coverage   74.11%   73.88%   -0.23%     
==========================================
  Files         100       99       -1     
  Lines        2712     2692      -20     
  Branches      443      457      +14     
==========================================
- Hits         2010     1989      -21     
- Misses        598      599       +1     
  Partials      104      104              

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[iamcarbon]

@abergs Ready for review.

[joegoldman2]

I just left a few comments. Otherwise, this migration looks awesome!

[iamcarbon]

This also addresses CVE-2024-21319

@abergs Let me know when you have a chance to review.

[abergs]

Looks great!