Improve test reliability

[martincostello]

• Write coverage reports for different projects to different files.
• Avoid build errors from bug in static asset publishing by disabling it.
• Update NuGet packages to their latest version where possible.
• Add various extra paths to .gitignore that should be ignored.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 1 line in your changes missing coverage. Please review.

Project coverage is 93.55%. Comparing base (1fa817f) to head (353eb7b).
Report is 5 commits behind head on master.

✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
...Injection/NewtonsoftServiceCollectionExtensions.cs	0.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #3423   +/-   ##
=======================================
  Coverage   93.55%   93.55%           
=======================================
  Files         110      110           
  Lines        3834     3834           
  Branches      719      719           
=======================================
  Hits         3587     3587           
  Misses        247      247           

Flag	Coverage Δ
Linux	93.55% <0.00%> (ø)
Windows	93.55% <0.00%> (ø)
macOS	93.55% <0.00%> (ø)

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