Refine metrics log in infrastructure

- Add interfaces to set/get metrics category in BasePreferenceController
  for descendants having a chance to get it.
- Set metrics category in DashboardFragment
- Automatically log metrics in onPreferenceChange of
  TogglePreferenceController
- Add support for TwoStateButtonPreference in TogglePreferenceController
  to make the preference generic

Bug: 137559984
Test: robotest
Change-Id: Ia7e0d24a3db1991b18e0286d9894570fa71247a3