add proper frame handling for cmd_pose

[ozanhakantunca]

In depth_controller_node.py;
The controller uses the cmd_pose topic to set z depth. But it does not take frame_id into consideration. the frame_id supplied in the message should be the frame of reference. the controller should adjust the base depth, relative to the supplied frame of reference.

[senceryazici]

Not completed until PR is merged :)