Models Generator Abstraction

[mroberts91]

It would be great if we could add an abstraction around the Infrastructure.ModelsBuilder.Building.ModelsGenerator to be able to override the concrete class with modified implementation and still request it from Dependency Injection.

For some edge cases that we have seen, we are able to take advantage of injecting additional interfaces in our generated models that allow the models to have access to distributed extension methods in NuGet packages.

There could be some additional abstractions made to TextBuilder and other classes in the Infrastructure.ModelsBuilder.Building namespace but the lightest set of changes would just be adding an IModelsGenerator interface to ModelsGenerator.

Currently, the concrete ModelsGenerator is injected into:

• ModelsBuilderDashboardController
• AutoModelsNotificationHandler

We are able to get around the fact that there is a concrete class being injected by hijacking requests made to the ModelsBuilderDashboardController and use our overriding ModelsGenerator to generate the models with the additional functionality, but it would be great to not have to intercept those requests.

[mroberts91]

PR open for this change #12210