Restructure repository

[andrewjong]

top level

- common/
-     docker/   # top level docker, points to sub-dockers to launch everything
-     ros_packages/
-         airstack_msgs/
- ground_control_station/
-     docker/
-     ros_ws/
- robot/
-     docker/
-     ros_ws/
- simulation/
-     docker/

We can chain build: build common first, then build individual workspaces.

[adityarauniyar]

I like this setup. I have created the repo ground_control_station/ that can be added as a submodule here. I also talked with @bradygm so that we can have the Airstack_msgs as a separate repo and use that as a submodule whereever needed.

[bradygm]

https://github.com/castacks/airstack_msgs/tree/main

[andrewjong]

Completed in #121 . Changed it so that instead of chain building, the ros packages under common/ simply get mounted under each docker container's ~/ros_ws/common