Add interface for services to share SessionIds

- adds ability to start/end sessions via StatusBarService's
SessionMonitor
- adds ability to register/unregister for session listeners via
StatusBarService's SessionMonitor
- adds logic for SystemUI to start/end Keyguard and BiometricPrompt
sessions in SessionTracker

Test: atest AuthControllerTest SessionTrackerTest
Bug: 213483562

Change-Id: I50ea003baae4fb89e311fa442fd52397e03e514c