impl(auth): id token adc flow should allow including email

[alvarowolfx]

Allow to specify if customers want to include email in the token claims when using ADC flow. This will enable email claim on sources that have to be set up for that, like MDS and Impersonated flows.

Towards #3449

[codecov]

Codecov Report

❌ Patch coverage is 86.36364% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 96.16%. Comparing base (1980f0d) to head (39abba2).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
src/auth/src/credentials/idtoken.rs	86.36%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3763      +/-   ##
==========================================
+ Coverage   96.11%   96.16%   +0.04%     
==========================================
  Files         146      146              
  Lines        5665     5682      +17     
==========================================
+ Hits         5445     5464      +19     
+ Misses        220      218       -2     

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[alvarowolfx]

will be updated after some PR like #3792 and #3789

[coryan]

Some minor changes that you need to do. A question around larger changes for testability.