Add shell autocompletion for available options

[FilipeBento]

Is your feature request related to a problem? Please describe.
Just like glow or gum, it would be nice to have shell autocompletions for freeze. Freeze deserves love too. ❤️

Describe the solution you'd like
A simple autocomplete file to add to the system. Doesn't necessarily need to be automated with new versions, as long as it gets updates when options are changed or added.

Describe alternatives you've considered
I use --help to bypass the problem, but an autocomplete file would be a quality-of-life improvement.

Additional context