Add master switch to enable/disable RESTRICTED bucket.

Adding a master on/off switch for the new bucket such that when it's off,
apps aren't be put into the bucket and any apps already in it are brought
out.

Bug: 155670438
Test: atest FrameworksServicesTests:AppIdleHistoryTests
Test: atest FrameworksServicesTests:AppStandbyControllerTests
Test: atest SettingsProviderTest:SettingsBackupTest
Change-Id: Iaeabefa14cbaa2d07a13555ecbc29e6fbf11a29c