[ros2] Port planar move to ROS2

[shiveshkhaitan]

Port gazebo_ros_planar_move plugin to ROS2.

Example usage:

    <plugin name="gazebo_ros_planar_move" filename="libgazebo_ros_planar_move.so">

      <ros>

        <!-- Add a namespace -->
        <namespace>/demo</namespace>

        <!-- Remap the default topic -->
        <argument>cmd_vel:=custom_cmd_vel</argument>
        <argument>odom:=custom_odom</argument>

      </ros>

      <update_rate>100</update_rate>
      <publish_rate>10</publish_rate>

      <!-- output -->
      <publish_odom>true</publish_odom>
      <publish_odom_tf>true</publish_odom_tf>

      <odometry_frame>odom_demo</odometry_frame>
      <robot_base_frame>link</robot_base_frame>

      <covariance_x>0.0001</covariance_x>
      <covariance_y>0.0001</covariance_y>
      <covariance_yaw>0.01</covariance_yaw>

    </plugin>

Migration guide at ROS 2 Migration: Planar Move

[chapulina]

@osrf-jenkins run tests please

[chapulina]

Works for me!

Could you add tests for the new conversion functions? Thanks!

It also needs rebasing.

[chapulina]

Great job!