Align 'controlled_frame' field in feedback with design (#7)

According to [the design document](https://github.com/fzi-forschungszentrum-informatik/fzi_robot_interface_proposal/blob/01a9c14a456fb76ccc6dd158a9cb0573a9ebb2da/source/proposal/index.rst#L237), the action feedback should contain a field called `controlled_frame`.

`tcp_frame` was the old name, prior to renaming it to `controlled_frame`.

action/FollowCartesianTrajectory.action

@@ -19,7 +19,7 @@ string error_string
 ---
 
 Header header
-string tcp_frame
+string controlled_frame
 CartesianTrajectoryPoint desired
 CartesianTrajectoryPoint actual
 CartesianTrajectoryPoint error