Add restore of Settings keys to

SettingsBackupAgent.RESTORE_FROM_HIGHER_SDK_INT_SUPPORTED_KEYS

Now that we have validators in place for all settings that are
backed up.

Also, add a setting to override restoreAnyVersion, which can be
modified by Phenotype.

Bug: 64988620
Bug: 72162887
Test: manual (P->P - master without changes to master with changes)
Test: manual (Q->P = API29 -> API28)
Test: a lot of other scenarios covered by our end-to-end tests
Test: a GTS test with both settings that don't have validators
      and have values that wouldn't pass validation will be added
      in vendor/xts
Change-Id: Ifaf94306984b5204c79648d48fd4056ad403196e