AnyKey support and service key injection

[tillig]

Resolves #1471.

Adds two primary features that allow for improved support for .NET 10:

1. Direct support for AnyKey: Microsoft.Extensions.DependencyInjection added the concept of AnyKey back in .NET 8, but the behavior of that became far more complex in .NET 10. For example, AnyKey items no longer get returned when resolving collections of AnyKey - they only get returned in individual resolution calls. This made AnyKey much more complex than simply "matching any key," necessitating a more integrated solution with core Autofac.
2. Ability to inject the service key into constructors or properties: M.E.DI has a [ServiceKey] attribute it uses to inject the service key into an object. With native support for AnyKey this seemed like a valuable feature to also bring into Autofac.

This should all be backwards-compatible with existing Autofac keyed services - it's just new API to support these new features. It should also make the Autofac.Extensions.DependencyInjection layer a bit easier to implement since we can map the Microsoft AnyKey to the Autofac AnyKey and it should "just work."

While working in here I did a couple of one-click optimizations to remove unused usings and similar minor housekeeping things. That increased the size of the PR but seemed not-unreasonable.

[codecov]

Codecov Report

❌ Patch coverage is 94.66019% with 11 lines in your changes missing coverage. Please review.
✅ Project coverage is 78.57%. Comparing base (17ccc0b) to head (1161e1f).
⚠️ Report is 36 commits behind head on develop.

Files with missing lines	Patch %	Lines
src/Autofac/ResolutionExtensions.cs	75.00%	2 Missing and 2 partials ⚠️
src/Autofac/Core/KeyedServiceParameterInjector.cs	95.00%	0 Missing and 2 partials ⚠️
src/Autofac/ParameterExtensions.cs	71.42%	1 Missing and 1 partial ⚠️
...Resolving/Pipeline/DefaultResolveRequestContext.cs	50.00%	0 Missing and 1 partial ⚠️
...atures/Collections/CollectionRegistrationSource.cs	97.05%	0 Missing and 1 partial ⚠️
src/Autofac/Util/InternalTypeExtensions.cs	50.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1475      +/-   ##
===========================================
+ Coverage    77.98%   78.57%   +0.59%     
===========================================
  Files          211      216       +5     
  Lines         5414     5611     +197     
  Branches      1150     1207      +57     
===========================================
+ Hits          4222     4409     +187     
- Misses         692      695       +3     
- Partials       500      507       +7     

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[tillig]

I've reviewed and iterated over this, verifying that the performance impact is negligible at best, and all the new tests pass. I'm going to call this good so I can see what it will take to update A.E.DI using the new functionality.