Add 'watch' command to CameraService

Currently there is no way to monitor tags and dump per frame data from
Camera devices without calling dumpsys, which in turn dumps a lot of
unnecessary information.

This CL adds a 'watch' command to CameraService which can be called
through `cmd`. 'watch' provides a path to manage tag monitoring without
dumpsys. 'watch' currently has four functions:
1. start <taglist>: starts mornitoring the provided tags in attached
                    devices.
2. stop: stop monitoring all tags
3. live: prints monitored information to the terminal live
4. dump: dumps any collected camera traces

This CL adds a function to camera device each for the three tag
monitoring function listed above.

Test: n/a
Bug: 199746421
Change-Id: Ia5ce13f6e50c82085afcc676309cdbffef915a41