Job Scheduler TARE page implementation

A Job Scheduler policy page is needed in the TARE developer options
settings to allow developers to both view and edit the current values of
all the factors under the job scheduler policy. The page uses a dropdown
so that the user can easily switch between the different policies. For
the factors with subfactors, the user simply clicks on the factor and
the subfactors wil pop up under it.

Bug: 191877052

Test: Manual (open Settings > System > Developer Options > TARE >
JobScheduler and verify all factors are there)

Change-Id: Icea6cda5e4b59d1736f85defcb9532839c3720f5