CompanionDeviceManager

This introduces an API for apps that support companion devices to provide a
more streamlined flow for pairing and setting up the device

Bug: 30932767
Test: Using a toy app, invoke the newly introduced API (CompanionDeviceManager),
 and go through the flow. Ensure filtering works, and device is returned to
 the calling app. Ensure the calling app can pair to the selected device.
Change-Id: I0aeb653afd65e4adead13ea9c7248ec20971b04a