Camera service: Support for device state change notifications

Add AIDL method for device-wide physical state updates (such as
folding/unfolding), and wire it up to the new camera provider HAL call.

Also clean up camera provider startup sequence - devices were being enumerated before
the new lazy HAL interface pointers were set up, resulting in many repeated calls
to getService even for a non-lazy HAL.

Also add unit test for CameraProviderManager to verify its section of
the callpath, as well as tests to check that the provider HAL and
hardware service manager aren't queried more than expected during
initialization.

Test: atest cameraservice_test

Change-Id: I5ec60fd9d93b7a2fe4d1a5854fad720a972fe8ea