Add @TestApi onBindCompanionDeviceService()

Add onBindCompanionDeviceService() method to CompanionDeviceService,
which is invoked from onBind(). This allows to track the state of
incoming Binder connection in CTS tests, which was not possible before,
since onBind() method in CompanionDeviceService is final.

Bug: 199435613
Test: atest CtsCompanionDevicesTestCases:SelfPresenceReportingTest
Test: atest CtsCompanionDevicesTestCases
Change-Id: I37cd3be15ed41b466ef9c6cead781299fd82356e