Finish the task of generic-izing support for child method classes

This is a follow-on to the previous release, to address issues identified while trying to apply that release to an actual use case (JUnit Cucumber support).

• LifecycleHooks - Add the getFieldValue method to the public interface; remove setFieldValue method.
• MethodWatcher - Add type parameter to this interface, and extend the TypeDiscloser interface. Change method signatures to replace arguments specific to FrameworkMethod with generic type and ReflectiveCallable object.
• RunAnnouncer - Remove type parameter. Only post notifications to RunWatcher providers that support methods of the current type.
• RunReflectiveCall - Set type of callable argument to its actual class (ReflectiveCallable). Remove object unwrapping specific to FrameworkMethod. Update invocation notifications to their revised signatures. Ensure that we don't die when logging debug messages.
• RunWatcher - Extend the TypeDiscloser interface.
• TypeDiscloser - New interface to require implementations of generic interfaces to publicize their supported type.