Additional settings tests and misc changes

[sm-msft]

This PR includes the settings related test changes from this original draft PR: #5114

Description

• New Windows user-mode storage API for writing MsQuic test settings
• Additional settings tests, including tests with stored settings (windows user mode only)
• Minor build documentation change

Testing

Existing tests + new tests

Documentation

N/A

[sm-msft]

I removed changes that update the last member of QUIC_SETTINGS struct in some macros because it was breaking downlevel tests. There seem to be an implicit contract on the size of this struct in the API - does this need any new documentation?

Original context: https://github.com/microsoft/msquic/pull/5114/files/48f6e9fad9ef371d7f8f3ae34bf53fb30dff14f2#r2113830016

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 86.00%. Comparing base (cfc5b5e) to head (9111215).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5132      +/-   ##
==========================================
- Coverage   86.05%   86.00%   -0.06%     
==========================================
  Files          59       59              
  Lines       18048    18027      -21     
==========================================
- Hits        15532    15504      -28     
- Misses       2516     2523       +7     

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[sm-msft]

Discussed Anthony's proposal to move the changes in this PR with #5133 and check them in as part of that PR. This is the plan for now.