Introduce IVibratorManager.aidl

Introduce interface for vibrator manager HAL.

A default implementation is made available to the existing
android.hardware.vibrator-service.example, which now provides a top
level devault IVibrator and a top level IVibratorManager with a
different vibrator in it.

VTS tests were also introduced for the new manager, and existing tests
for IVibrator where changed to run in all top level and managed HAL
instances found on a device.

Bug: 166586119
Test: atest VtsHalVibratorTargetTest
      atest VtsHalVibratorManagerTargetTest
Change-Id: Iec9175167e795bc03c4f3d873e2ac6682ed52512