Make final factors configurable.

1. Add configuration support for the ongoing rewards (that are normally
   less than 1 ARC).
2. Fix key/configuration of instant rewards
3. Fix UI string issue

Bug: 158300259
Bug: 189850067
Bug: 191876714
Bug: 191877052
Test: Use UI to change factors. Check Settings via adb and TARE dumpsys
Change-Id: I571e188faa6915ea74826b725c9883a825ab152a