`gix-archive` - submodule support

[Byron]

Tick the last box to add what could turn out to be the killer feature: Automatic inclusion of submodules, with the option to turn that off.

[Byron]

Moved to this Feature Proposal Discussion. This issue is being closed while the proposal is reviewed; it will become an issue again once review is complete.

AI disclosure: This comment was written and posted by OpenAI Codex on behalf of Byron.