zsh-completion: update hostnamectl

hostnamed: introduce new "embedded" chassis type We really don't want to get lost in adding fridge, car, plane, drone, or whatever else, hence add a generic term "embedded" cover all the cases where the computer is just part of something bigger, and not at the focus of things.

shell-completion: add hostnamectl set-deployment

shell-completion,man: beef up chassis completions and description Parameters to hostnamectl command are not optional and should not be marked as such in the man page.

completions: fix/augment zsh completions for systemd-nspawn, busctl, loginctl, hostnamectl, localectl, machinectl

zsh_completion: Fix single letter args Things like -n to specify the lines to show with systemctl and journalctl accepts syntax like: journalctl -n4 systemctl -n14 Previously, typing `-nXX <tab>` where XX is a number, zsh would try to complete an integer. Now it will see the XX and use the _journalctl_none completion. This is also how any of the single letter options that take arguments work as well.

zsh_completion: Move helper function to autoload _hosts_or_user_at_host was used by 6 different completions, and previously was in all 6 of those files. I moved it out to its own file, _sd_hosts_or_user_at_host. This will be autoloaded for use in other completion functions. It also allows external completions to use this function by simply calling _sd_hosts_or_user_at_host as in the systemd completions.

zsh_completion: Split out zsh _hostnamectl