Fixed arm geometry message timestamp

[kssummer]

Launching rviz (either manually or from the navigation launch file) would spam the log with error messages relating to the arm geometry broadcast messages:

[ WARN] [1664852191.766332164]: TF_REPEATED_DATA ignoring data with redundant timestamp for frame arm at time 0.000000 according to authority unknown_publisher
Warning: TF_REPEATED_DATA ignoring data with redundant timestamp for frame arm at time 0.000000 according to authority unknown_publisher at line 278 in /home/sean/ros_catkin_ws/src/geometry2/tf2/src/buffer_core.cpp

This change adds the timestamp before the broadcast is sent to resolve this issue

[kssummer]

@XRobots Please approve/merge if you want. I was getting a lot of log spam when launching rviz; it made it hard to get any meaningful messages