Add RViz UserGuide

[LeweC]

As discussed in PR #3908 and initial Issue #3864.

I am not sure where this UserGuide would fit in the current structure.
I only came up with the idea of having it in the Tutorials/RViz folder because I could not find a section for UserGuides and needed something to commit to open this PR.

Maybe this is the right place for it, or did you have a better idea?

Also, I will be a bit busy until the end of January. So if anyone wants to replicate this UserGuide for ROS2, feel free to do so.
There is some more information in the above mentioned PR. If not, I have time in February to focus on both PRs and maybe we can even merge them soon.

[clalancette]

Maybe this is the right place for it, or did you have a better idea?

Yes, this is exactly what I had in mind. With this directory in place, we can then go on and put the tutorials in #3908 in the same place.

I'll take a quick look at the rest of this and leave some feedback.

[LeweC]

Okay, now I have time to work on this again. While I do that, do you have any ideas or recommendations on how to deal with the two linked youtube videos in there? Do you know or have any new RViz examples or should we just not link to a video there?

[clalancette]

Do you know or have any new RViz examples or should we just not link to a video there?

Let's just leave them out for now. We can always add in videos again later if we decide to make something.

[LeweC]

Okay, I think this version is ready for a first review. Here are a few notes:

• I did not include the link to the Troubleshooting page in the original UserGuide because that is a whole new task.
• I am not entirely happy with how the table of "Built-in Display Types" looks when I build it locally, because you have to scroll to see the links.

[clalancette]

Thanks for picking this back up! I've done a first pass review, please take a look.

[clalancette]

This is definitely getting closer! Thanks for iterating.

[clalancette]

I've left a lot of comments, but we are just down to nitpicks now. Once this round is done, I'm pretty happy with this and I'll run the tests again.

[clalancette]

There are some linting errors; see the GitHub jobs for those.

Once those are fixed, I'll suggest marking this as "Ready for Review", and we can merge it in. Thank you for all of the hard work here.