Fix gh 398 hash collision mitigation

[jwoodmanbuildium]

I've removed the temporary fix to mitigate hash collisions & added a new opt-in behavior for tracking instances using a concurrent dictionary & instance identifier struct.

The new optional InstanceMapBehavior has been added to the hosting extensions & container/scope constructors. The default value will maintain the integer-based hash approach. Passing a Dictionary value will update the tracked services implementation to use a concurrent dictionary in place of the hash map. When a dictionary is used, the InstanceIdentifier struct will be tracked through its IEquatable implementation, rather than the hashcode.

[jwoodmanbuildium]

@jeremydmiller - I've went ahead and tackled this (#398) by abstracting the underlying data structure used to track the services.

[jeremydmiller]

@jwoodmanbuildium Hey, there are changes here to tests that don't seem to be related. And also, #sadtrombone, there are breaking API changes. You cannot add optional arguments to an API unless you are making a full point release. You'd have to add overloads instead.

[jwoodmanbuildium]

@jeremydmiller - Overloads have been added in place of adding optional arguments to the previously updated methods & constructors.

Regarding the test changes:

• Bug_398_service_registry_hash_collisions has been deleted as it's no longer needed with the alternative instance identifier behavior
• integration_with_aspnetcore requires an update as it's failing with the new implementation of the hostbuilder extensions. AddLamar now registers the IServiceProviderFactory using an implementation factory, and the default registered type is now being returned as IServiceProviderFactory<T> instead of the implementation type.