Improve multi user settings screen

- Added switch and user delete functionality to details screen.
- Added robo tests.

Screenshots: http://shortn/_S6fbIMhAYO
Bug: 142798722
Test: Run robo tests with this command:
  make -j64 RunSettingsRoboTests ROBOTEST_FILTER="com.android.settings.users.*SettingsTest"
Change-Id: Id51c12c5470e30e2dffe93f3bd8c22380d8bdc1f
16 files changed