Update to build with .NET 8, update dependencies

[tillig]

• Updates Autofac core dependency to 8.0.0, which includes a breaking Autofac core change so the configuration library increments to 7.0.0 major release. This also includes some differences in how constructor discovery is done (public vs. internal) so changes here were made to consistently throw constructor-not-found-exceptions as needed.
• Update all other internal dependencies including MS configuration. This changes some minor behaviors since .NET 2 - including changing handling of empty objects/lists in configuration.
• Update build to use .NET 8 SDK, but still target netstandard2.0 and netstandard2.1.
• Fixes to nullable annotations.
• Switch embedded resources to build in the new VS Code compatible way.
• Standardize on US English for some spellings.
• Added tests to improve overall coverage.

[tillig]

When this is merged I'll release a full major update and it will include the fix for #44 from @pnagoorkar.

[codecov]

Codecov Report

Attention: Patch coverage is 89.65517% with 3 lines in your changes missing coverage. Please review.

Project coverage is 73.74%. Comparing base (ecfb304) to head (59dbc8c).

Files	Patch %	Lines
...c/Autofac.Configuration/Core/ComponentRegistrar.cs	75.00%	2 Missing ⚠️
src/Autofac.Configuration/Util/StringExtensions.cs	0.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop      #46      +/-   ##
===========================================
+ Coverage    65.54%   73.74%   +8.19%     
===========================================
  Files           11       10       -1     
  Lines          386      358      -28     
  Branches       119      117       -2     
===========================================
+ Hits           253      264      +11     
+ Misses          70       42      -28     
+ Partials        63       52      -11     

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[alistairjevans]

Looks good 🐧