Simplify conditional/contextual injection based on parent collection item

[dotnetjunkie]

Simple Injector users keep struggling with a particular use case that allows them to apply a repeating class over collection of other types.

The following issues show use cases for this:

• https://github.com/simpleinjector/SimpleInjector/issues/869
• https://github.com/simpleinjector/SimpleInjector/issues/886
• https://github.com/simpleinjector/SimpleInjector/issues/902
• https://stackoverflow.com/questions/65911575/chaining-dependency-injection-in-net-core-3-1
• And perhaps https://stackoverflow.com/questions/71588273/conditionally-register-collection-in-simple-injector