message: added robot ips in dual arm example control launch
diff: <?xml version="1.0" ?>
  <launch>
  <arg name="robot_id" default="panda_dual" />
  + <arg name="robot_ips" default="{panda_1/robot_ip: robot_1, panda_2/robot_ip: robot_2}" />
  <arg name="rviz" default="true" />
  <arg name="rqt" default="true" />
  <include file="$(find franka_control)/launch/franka_combined_control.launch" >
  <arg name="robot_id" value="$(arg robot_id)" />
  + <arg name="robot_ips" value="$(arg robot_ips)" />
  </include>
  <group ns="$(arg robot_id)">
  