Launch arguments support bool instead of string types only

The priorliy used string comparison would not work when passing
proper bool types when including the launch file. This fix
allows using both string and bool values.

Author: henningkayser

ur_robot_driver/launch/ur_control.launch.py

@@ -192,11 +192,11 @@ def controller_spawner(controllers, active=True):
         "freedrive_mode_controller",
         "tool_contact_controller",
     ]
-    if activate_joint_controller.perform(context) == "true":
+    if activate_joint_controller.perform(context):
         controllers_active.append(initial_joint_controller.perform(context))
         controllers_inactive.remove(initial_joint_controller.perform(context))
 
-    if use_mock_hardware.perform(context) == "true":
+    if use_mock_hardware.perform(context):
         controllers_active.remove("tcp_pose_broadcaster")
 
     controller_spawners = [