Setup CI

[chapulina]

Add GitHub actions-based CI that runs on every push and PR.

It uses binaries for ROS and Gazebo dependencies, pulled from https://packages.ros.org, and compiles from source all the repos in buoy_all.yaml.

Then it tests all buoy repos, including buoy_msgs. I think we should just rely on the ROS buildfarm to run CI for the messages package eventually, but until we're ready to bloom it, we can test it here.

CI is currently failing the copyright check, which should be fixed by #6

[quarkytale]

Had retriggered checks, but its only failing for copyright

[chapulina]

Thanks for the review, @quarkytale ! Now that #2 and #5 have been merged, I expect the linters to fail.

Once CI comes back, if only the linters are failing, I'll merge this PR, and you can work against main to address those linters as part of #3 until CI is 🟢 . If something else fails, like the build, I'll address it in this PR before merging.

[chapulina]

Ok, only linter errors:

	  1 - copyright (Failed)
	  2 - cppcheck (Failed)
	  3 - cpplint (Failed)

Merging!