Additional features, like a shared .env, registry integration, and alternate RMW options

[pauliusblartman]

There could be some changes which may be helpful for your template. Mostly just adding a shared .env and container registry, but wanted to make a request. Still plan on adding a few things like version locking for rosdep but thats not the highest priority right now.

[anglesideangle]

Thanks for the pr

A few things:

• zenoh is definitely a good idea - i use it for everything as well so i'll definitely look into it
  • you use EXPOSE a few times in the dockerfile to enable zenoh, but i'd imagine the --network=host bit in the makefile should implicitly cover this. perhaps an equivalent to make dev but for running the final image would be useful
  • i'm not sure what is the ideal way to run zenoh from within the container, since you can't have multiple CMD. letting the user add rmw_zenohd to their ros launch would work, as would more complex solutions like an orchestration system inside the container, although i'd like to avoid the latter
• not a fan of moving the ros2 examples repo out of git submodule because it implies it's supported code / part of the template
• the make push command is very useful