This migrates flags inside DeviceIdleController to DeviceConfig.
DeviceConfig is the recommended way and using it means
that we only operate/parse the set of flags that changed instead of
every single flag whenever one of them changes.
Bug: 124466289
Test: atest CtsHostsideNetworkTests
Test: atest FrameworksMockingServicesTests:DeviceIdleControllerTest
Test: atest SettingsProviderTest:SettingsBackupTest
Change-Id: I7fff451b641eee43a13e77df7b40db5b3af16d58
1e55861ed4