Add shell autocompletion for ignited

[silenceshell]

Add completion for ignited.

root@pve:~# ignited # press tab twice here
completion  daemon      gitops      version

[luxas]

Thanks @silenceshell, this looks good 😄
I think you need to run a make tidy locally to autogenerate the CLI documentation

cc @twelho who knows this code better than me

[silenceshell]

@luxas make tidy done, please have a look

[twelho]

LGTM, thanks! 👍