This fixes an issue where `TestBed.overrideComponent(MyComp, {})`
would remove some properties including `providers` from the component.
This was due to the override not properly dealing with getter fields
on subclasses.
Closes#9729
BREAKING CHANGE:
`Type` is now `Type<T>` which means that in most cases you have to
use `Type<any>` in place of `Type`.
We don't expect that any user applications use the `Type` type.