Add estimated time remaining text to QS

- Add an API to BatteryController to get an estimated time remaining
string.
- BatteryController will now check up to once per minute what the
estimated time will be and builds the string using PowerUtil.
- If the "show percentage" setting is on, the estimated time remaining
string (and battery icon) will show next to the system icons in QS
- Also make the battery percent in QS obey the setting

Test: visual
Bug: 116481529
Change-Id: Iaafa00127c8b8baae40956254a1237c8b7ac079b