Camera3Device: Add dumpsys monitoring of request/result metadata

Add new -m dumpsys option to cameraservice dump for monitoring
changes in selected metadata values in requests and results.

This option takes a comma-separated list of metadata keys, or the
shortcut value "3a", which expands to all the "android.control" tags.

In subsequent dumpsys calls, the last 100 changes to the tags being
monitored are listed.

The monitoring must be turned on once the camera device is running.

Bug:
Change-Id: If8938b30611ccafa86c2c4a06e57fc72680f827b