Cleanup the Polly and Polly.Specs codebase

[martincostello]

• Suppress extant occurences of code analysis warnings inline in the code and re-enable suppressed rules.
• Fix remaining IDE/formatting suggestions in Polly.Specs.

Resolves #1290.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 85.35%. Comparing base (7148503) to head (ab4d596).
Report is 10 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2467   +/-   ##
=======================================
  Coverage   85.35%   85.35%           
=======================================
  Files         312      312           
  Lines        7464     7465    +1     
  Branches     1121     1121           
=======================================
+ Hits         6371     6372    +1     
  Misses        908      908           
  Partials      185      185           

Flag	Coverage Δ
linux	85.35% <100.00%> (+<0.01%)	⬆️
macos	85.35% <100.00%> (+<0.01%)	⬆️
windows	85.32% <100.00%> (+<0.01%)	⬆️

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