Intra-process comm not supported due to transient_local durability

[roncapat]

Currently, robot_state_publisher can be used as a composable node, but with Intra-Process disabled. It would be desiderable to allow its enablement.

[sloretz]

Mind trying if intra-process works when you override the qos parameter?

The parameter name should be something like: qos_overrides./robot_description.publisher.durability and you can set it to volatile.

[Yadunund]

@sloretz's solution would work but often times downstream subscriptions expect a transient_local durability. Hence, I've opened #220. Could you give that a try?