Remove Critical/Unsecure property/method proxies and CAS-related code

[h3xds1nz]

Description

Slowly coming to an end, but an additional batch of CAS-related obsolete / dead code, this time the "Critical" and "Unsecure" proxies and demand methods that do nothing these days. That includes all bunch of security notes and other comments.

It is mostly scoped commit by commit to make the review as smooth as possible besides CriticalFromVisual where the fixer wasn't kind to me and I've noticed way too late, so hopefully all issues are fixed in the latest commut.

Code that I've removed in previous PRs already is untouched (though it ain't extra nice to keep hitting the same code 6 months later, not gonna lie). But after all these things are merged, it should be clean finally. Maybe 1 exception string.

Customer Impact

Cleaner codebase for developers, a bit of perf in some cases.

Regression

No.

Testing

Local build, sample app run.

Risk

Should be low, it is mostly just renames and some removals/code moves.

Microsoft Reviewers: Open in CodeFlow

[codecov]

Codecov Report

Attention: Patch coverage is 4.64396% with 308 lines in your changes missing coverage. Please review.

Project coverage is 11.06411%. Comparing base (2ded801) to head (fe51e42).

Additional details and impacted files

@@                 Coverage Diff                 @@
##                main      #10701         +/-   ##
===================================================
+ Coverage   10.95887%   11.06411%   +0.10524%     
===================================================
  Files           3310        3310                 
  Lines         664667      664464        -203     
  Branches       74667       74653         -14     
===================================================
+ Hits           72840       73517        +677     
+ Misses        590685      589809        -876     
+ Partials        1142        1138          -4     

Flag	Coverage Δ
Debug	11.06411% <4.64396%> (+0.10524%)	⬆️

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