Minor Dockerfile optimizations

[amarburg]

Changes Made

Cleaned up and focused version of #226.

An opinionated cleanup of the dockerfile. Includes:

In the "ci" image:

• Move the apt-get above the "copy"
• Only copy */package.xml (requires the recent "copy --parent" syntax in the Dockerfile) and blue.repos into the ci image, rather than the full contents of this repo. I believe this prevents changes to e.g. files in .docker/ from breaking cache.
• vcs import < blue.repos so rosdep dependencies for those packages are also installed in the CI image.

In the "robot" image:

• Move the apt-get for gstreamer above the "copy" so changes to this repo don't break that cache
• Minor cleanup to installation of geographic libs

This doesn't include some of the more opinionated hadolint changes (e.g. gosu, etc). This PR is focused on moving relatively static steps (apt-get) above cache-breaking changes (pulling files from the local filesystem)

Associated Issues

None

Testing

Completed "joystick teleoperation" demo with built images in rolling and jazzy

[amarburg]

Hm, odd that ROS-Industrial CI is now breaking. Debugging ...

Hm, so ROS-industrial CI is looking for mavros, mavros-extras etc. Which makes sense. The question is how did it ever work?

[amarburg]

As a note, as expected, industrial CI does work if we force it to run on "humble" (where mavros is available through rosdep), but fails for "rolling" (and presumably "jazzy")

[amarburg]

As noted, industrial CI tries to install mavros viaapt, which is currently not available for rolling (#248).

CI does work if we force it to use Humble, for which there's a binary image.

Note this is just the ros_industrial CI stage, not building the Docker images (where Mavros is built from source for rolling/jazzy.

[evan-palmer]

Thanks for looking into that. Because we know it's an issue with MAVROS, It's not a big deal if the CI fails in this PR. We can just update the CI stage in #241 to use the new mavros stage.