Migrate InteractiveMarkerDisplay

[jacobperron]

Closes #98

Depends on ros2/ros2#770

Some changes since ROS 1 based on discussion in ros-visualization/interactive_markers#42:

• The feedback publisher is now maintained by the interactive marker client (not RViz)
• Since clients and servers now communicate with a mix of services and topics, the ROS topic property should be replaced with custom property for interactive marker server discovery.

[jacobperron]

Opening for visibility. This isn't quite ready for review as there are some things I'd still like to do:

• Add a custom property object for selecting interactive marker servers to connect to (as eluded to in the description).
• Review code for areas that can be refactored for the better
  • So far I've done the minimum to get the code to compile and run without crashing, but there may be places in the code that might be ripe for updating.
• Add tests. Visual tests would be nice.

For those interested in trying out the display, you can check out this branch and clone the interactive_markers package to your workspace: https://github.com/ros-visualization/interactive_markers/tree/ros2.

I've ported the demos too. You can find them here: https://github.com/jacobperron/visualization_tutorials/tree/jacob/ros2

[jacobperron]

Planning to add some tests still, but the rest is ready for review.

[jacobperron]

I've been working on tests, but it looks like we should add/extend mock objects.
@wjwwood If it's alright with you I'll merge this (pending CI) and follow-up with improving test coverage.

• Linux
• Linux-aarch64
• macOS
• Windows

[wjwwood]

Sounds good to me.