Revamp the battery saver page

1. Make BatterySaverSettings extend from DashboardFragment
2. Add new layout
3. Add battery saver controller

Future cl will add controllers for seekbar and button

Bug: 72228477
Test: RunSettingsRoboTests
Change-Id: I21fb62aef874c04eca2988271f2fd9d7aacb0c6c
13 files changed