Camera: Add support for readout timestamp

- Add new CameraCharacteristics key to indicate readout timestamp
  support.
- Add onReadoutStarted() in CaptureCallback
- Add READOUT_SENSOR time base for OutputConfiguration.

Test: atest Experimental2022SystemTest
Bug: 229773853
Bug: 229097448
Change-Id: Icf831367d3ac92dfd0ae439724d1433968b36dd6