Add a guide for those migrating from ROS1 and catkin_tools

[agyoungs]

I think it would be pretty useful to have a quick guide that shows users of catkin_tools how to effectively use colcon. A lot of people I've worked with (who are technically strong in ROS1), have echoed the same complaints that "colcon is cumbersome and lacks much of the functionality of catkin_tools".

A deeper dive into this myself has led me to appreciate a lot of what colcon can do, but I still very much feel it is cumbersome compared to catkin_tools. I've only recently learned that many of the things that I want, are likely already implemented in colcon, but it wasn't simple for me to find.

So that led me to open up this issue to create a guide for catkin_tools users. I think a very large portion of ROS1 users would benefit from this guide. Unfortunately, I'm not a colcon power user at this point so I don't think I can write the PR needed for this, but maybe I can define a good list of common catkin_tools use cases.

• Build anywhere within a colcon workspace
  • It looks like this might be possible once Alternative implementation colcon-top-level-workspace#2 is merged in
• Set up build profiles for a workspace (build in Release with Debug info, symlink install, etc.)
  • It looks like this exists as well, but the documentation isn't merged in: Document colcon_defaults.yaml feature #89
• Clean a workspace/package
  • It looks like there's an extension for this, however it's not installed by default? Also, I missed documentation on this if there was any: https://github.com/colcon/colcon-clean
• Change directories to another package
  • This is related to the roscd command and not so much catkin_tools, but I still find it useful here
  • It looks like this exists, but again is a separate install and you have to source the script before you can use it. https://github.com/colcon/colcon-cd
• I personally really liked the output colored format of catkin_tools. I'm not sure if there's a way to customize that output for colcon in a similar way.

Sorry if this reads as a bunch of feature requests, but ultimately I just want to understand how to do the things I mentioned above the correct way with colcon. I think a guide with examples of each of these items would be extremely useful. I'm willing to write it all up and create a PR if I can get some feedback on the right way to use some of these tools (or pointed to resources that already exist).