[Apizr] Deprecated Optional package removed from code & doc

[JeremyBP]

I just removed the now deprecated Apizr.Integrations.Optional package from generating code and documentation. Optional monad pattern wasn't used that much, complicated to understand and refreneced Optional.Async package was no longer maintained for years now.

I's a breaking change for those who are using Refitter with "WithOptionalMediation" but they still can reference the deprecated integration package manually. Like I said, I bet almost no body use it actually.

I updated the doc of course and the tests.
I upgraded build test referenced packages too.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.89%. Comparing base (b34738d) to head (2f951c1).
Report is 8 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #539      +/-   ##
==========================================
- Coverage   97.41%   91.89%   -5.52%     
==========================================
  Files          51       51              
  Lines        2517     2654     +137     
==========================================
- Hits         2452     2439      -13     
- Misses         42      181     +139     
- Partials       23       34      +11     

Flag	Coverage Δ
unittests	91.89% <100.00%> (-5.52%)	⬇️

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[christianhelle]

@JeremyBP looks good to me

Thanks for the contribution