Align MSBuild properties across all projects

[joegoldman2]

• Set TargetFrameworks to $(SupportedTargetFrameworks)
• Align LanguageVersion to 11
• Set ImplicitUsings to enable in root Directory.Build.props
• Miscellaneous cleanup

[codecov-commenter]

Codecov Report

All modified lines are covered by tests ✅

Comparison is base (15263ca) 77.50% compared to head (2ccd1af) 77.50%.
Report is 1 commits behind head on master.

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Additional details and impacted files

@@           Coverage Diff           @@
##           master     #437   +/-   ##
=======================================
  Coverage   77.50%   77.50%           
=======================================
  Files          98       98           
  Lines        2716     2716           
  Branches      445      445           
=======================================
  Hits         2105     2105           
  Misses        492      492           
  Partials      119      119           

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[iamcarbon]

May we Add disable to main Fido2.csproj for now. I prefer these to remain explicit on that project and defer a decision on whether we should enable.

[iamcarbon]

Aside from disabling implicating using on Fido2.csproj, everything else looks good to me.

[iamcarbon]

LGTM