Respect XDG_CONFIG_HOME when generating systemd unit

[Ram-Z]

Addresses #307 (comment).

Possibly a better approach would be to let package maintainers install this unit file in /usr/systemd/user, but this would break the "single file" design.

[muayyad-alsadi]

I would love if we add --global option as in the referenced comment.
I would love if we keep the sudo in the help.

[Ram-Z]

I would love if we add --global option as in the referenced comment.

The --global option only makes sense with -a create-unit, I wasn't sure how to introduce it nicely. Happy to take advice on how you'd like this handled.

However, I'm not convinced it should exist at all. podman-compose wants to be rootless, providing an easy way to install the systemd unit to the users home directory only is perfectly fine.

I would love if we keep the sudo in the help.

The point of this MR is to install the user systemd unit in the users home directory where sudo is not needed.

[muayyad-alsadi]

However, I'm not convinced it should exist at all. podman-compose wants to be rootless, providing an easy way to install the systemd unit to the users home directory only is perfectly fine.

a typical valid use case is to install podman-compose rootful and used rootless.