GitLab

Refactor the `Invoke` and `InvokeWithoutArgs` actions:
 - Replace pump'd classes and functions with templates.
 - Make the polymorphic actions be polymorphic functors instead.
 - Fix Invoke(Callback*) to work with subclasses of the callbacks, instead of trying to diagnose that in gmock_doctor.

PiperOrigin-RevId: 229604112