Snapcraft ROS plugins should be using catkin_pkg instead of fetching all deps with rosdep

[Kyle Fazzari]

rosdep can't discriminate between build-time and run-time dependencies. As a result, ROS snaps include build dependencies when they don't need to, thus making them larger than necessary. Snapcraft should be using catkin_pkg to manually pull dependencies out of each package.xml.

[jeremie (artivis)]

Note:
- This only concerns ROS plugins V1.
- It will likely be resolved directly on rosdep side by the (pending as of the time of writing) PR https://github.com/ros-infrastructure/rosdep/pull/789.