Set owner for trees.

[jeppester]

I'm making a butane config for running nextcloud, based on this

If possible I want the containers to run rootless, which I believe is possible if I place the containers in .config/containers/systemd.

My plan is to have a .config-folder in my repo, that I can simply copy to /home/coreos by using the trees functionality.

Unfortunately it looks like trees does not support setting an owner and will simply default to root.

Do I need to add the files one-by-one to butane in order to set the owner to coreos, or is there another way to set the owner for all the files during the install?

Also: Would you accept a PR that adds user and group to the configuration for trees?