Makes it possible to robo-test Settings app fragments.

This adds bunch of shadow/placeholder classes and logic to handle
references to Android internal resources or newly added classes/methods
that Robolectric hasn't yet picked up.

Developers can follow ManageApplicationsTest example to use the shadow
classes and the utility method to start ther fragment in their
robolectric tests.

Bug: 33431346
Test: This is a test improvement CL. RunSettingsRoboTests still passes.
Change-Id: I943ab871631cb8c368d9f9db481c00558c5c4d1f