Command completion

[carzacc]

I haven't found any tab-completion scripts for this project. I usually find them really useful both when I don't remember an exact command or option name and to avoid mistakes when typing the command in general, as well as to speed up general usage. I'm sure many others do as well.

In addition to the usual reasons, I believe that it might be particularly useful as a way to hint to the user whether some feature they know from docker-compose is implemented in podman-compose.

I could work on a completion script for Bash, as I already have some experience with that, if the maintainers agree that it might be useful.