Describe the feature or problem you’d like to solve

It is currently not possible to set a parent issue/sub-task when creating/editing issues:
https://docs.github.com/en/issues/planning-and-tracking-with-projects/understanding-fields/about-parent-issue-and-sub-issue-progress-fields

Proposed solution

I think it would be enough to add these options: --set-parent [ID] and --unset-parent [ID].

Additional context