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: Ied67290e8fed87feb0a60a3f2c40eb91cc57988e
16 files changed