Feature/houston -- an alternative process manager

[mvukov]

I am exploring, for a while now, how to use an alternative to the native ROS process mgmt. Some stuff that bothers me with the current situation:

• It's in Python. I have to drag along the interpreter. Write unit/integration tests for launch stuff (yes, I do that).
• Configuration: overrides, the launch mechanism dumping things to tmp files -- would like to have all final params in a single file.
• Have deterministic order of starting up and tearing down of the nodes. When using iceoryx (classic) this is handy. Iceoryx has a daemon that should be started first and be torn down last; it has a built in monitoring functionality that can interfere with signal handlers of ROS nodes and screw that up.

I kinda think that most of the deployment checks can be done in build time -- if a launch target builds it should mean that the launch config is OK. No surprises.

Searching the web the best thing I could find is https://github.com/malyn/groundcontrol/tree/main. I imported it here and patched since build broke with a newer rust compiler.

Demonstration

cd examples

bazel run //chatter:houston_chatter

# OR

bazel run //zero_copy/houston:zero_copy_houston --@cyclonedds//:enable_shm=True -c opt

The zero-copy example is a bit more complicated, and therefore more interesting.

One of the nice things about groundcontrol is that the processes are torn down in the reverse order.

This is very very early prototype but hopefully illustrates ideas.

Pay attention that all Python launch stuff is basically executed during build in exec config. No Python dependencies in runtime at all (at least for those two examples). Didn't want to invent a DSL nor use YAML or something third. Deployment composition is done in Python for convenience.

@ahans @lalten @rdelfin WDYT?