Add entrance for B&R sound related settings.
Bug: 278975761
Test: manual, need to open aconfig flag.
Change-Id: I5396e9e260aea1ece3a507ee322c73308f69f94a
Add OnboardingFeatureProvider which will be used to B&R sound settings and
related tasks.
Bug: 289512753
Test: FakeFeatureFactory
Change-Id: I25e3b1f105ce0970cdf651400c153d8b4733029b