rqt_jtc: Check for interface type when adding joint names

The JTC RQT gui extracts joint names from the required state interfaces
of a controller matching the JTC name pattern. If that controller
doesn't contain limits for all joints, that controller will be ignored.
Therefore, of the controller has setup a speed scaling state interface,
that will show up in the list of joints, while there are no limits
configured.

This commit only adds state interfaces which are of type "position" or
"velocity" to the list of joints.

Author: fmauch

rqt_joint_trajectory_controller/rqt_joint_trajectory_controller/joint_trajectory_controller.py

@@ -465,8 +465,10 @@ def _jtc_joint_names(jtc_info):
     joint_names = []
     for interface in jtc_info.required_state_interfaces:
         name = "/".join(interface.split("/")[:-1])
+        interface_type = interface.split("/")[-1]
         if name not in joint_names:
-            joint_names.append(name)
+            if interface_type == "position" or interface_type == "velocity":
+                joint_names.append(name)
 
     return joint_names