Fix how comms bridge gets its own ROS_IP
Context
Comms bridge fails to set up its own ROS_MASTER_IP because we haven't pass the proper ROS_IP
to be evaluated. This issue creates the need of having a mechanism to get an ip from a certain source (in this case it's the pod ip).
Change
This MR adds a new env var to the Container data structure to allow developers specify if env vars should be passed as values or they should be gotten from an external source. In this MR we've only implemented a mechanism to get the IP from the same pod.
Other information
Additional documentation
Edited by Marcos Huck