Auto Master/Slave

[boitumeloruf]

In camera_aravis for ROS 1, there is a functionality where a camera can be defined as a 'master camera'. This has the effect, that the camera will periodically publish data on auto control features, e.g. Balance ratios, exposure time, gain, ...
Furthermore, other cameras can be defined as 'slaves'. These cameras will then subscribe to the data that is published by the master camera and will adjust the corresponding values published by the master camera accordingly. This allows the have multiple cameras with the same auto controls, which are specified by a predefined master camera.

This feature is helpful and should also be implemented for camera_aravis2. In this, the feature set for which settings are to be published by the master camera should also be made configurable by the user, similar to the way dynamic and diagnostic parameters are configured.