Add power management settings into Settings->Battery

The items been added to group are: Adaptive brightness, Sleep.
Battery saver has been moved into this group as well.

Also refactor the code a little bit to make it fit the
preferenceController. Whole refactor of PowerUsageSummary and
PowerUsageDetail will be tracked in b/34386721

Bug: 34279051
Test: runSettingsRoboTests & Screenshot
Change-Id: I702d8479d1b80f7e9cf1a46752c75bf5d189e0f6