This method accepts multiple flags and overrides the values of all flags
in the provided namespace atomically. If any listeners are registered
for that namespace it will also trigger a callback with all of the flags
that were changed (added, updated, or removed).
Test: atest FrameworksCoreTests:DeviceConfigTest
atest FrameworksCoreTests:SettingsProviderTest
atest SettingsProviderTest:DeviceConfigServiceTest
Bug: 136135417
Change-Id: I2e496a3807493750ba8891dd6390055c919b5f45
4bd0a6a259