Update build, analyzers to match core Autofac

[tillig]

• Change build to GitHub Actions. This means new Autofac.Multitenant packages will be published in GitHub Packages rather than on MyGet.
• Update analyzer rules to match core Autofac.
• Fix analyzer issues due to new rules.

[codecov]

Codecov Report

❌ Patch coverage is 80.00000% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 93.57%. Comparing base (349c4f6) to head (d0c1d47).

Files with missing lines	Patch %	Lines
src/Autofac.Multitenant/MultitenantContainer.cs	80.00%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop      #43      +/-   ##
===========================================
- Coverage    93.66%   93.57%   -0.10%     
===========================================
  Files            5        5              
  Lines          142      140       -2     
  Branches        36       36              
===========================================
- Hits           133      131       -2     
  Misses           3        3              
  Partials         6        6              

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