Delete a backup

[OpenBagTwo]

GIVEN Alex already has gsb installed on her system and is using it to track a save state

WHEN she opens a terminal, navigates to the directory where her save game lives and runs the command:

gsb delete <commit-hash-or-tag>

THEN:
The selected backup is deleted (with the incremental changes from that backup getting squashed into the next backup)

SO that she can have a cleaner backup history (and potentially recover some disk space the next time she does a git-gc

Notes

• gsb delete should accept multiple backup identifiers
• gsb delete must accept any backup id in the form provided by gsb history. Supporting full commit hashes / commit short-hashes for tagged backups would be ideal but isn't a dealbreaker.
• gsb delete with no identifiers should generate a prompt (like you get with gsb rewind). Bonus points if this can be a fully interactive multiselect.
• In lieu of Backup cleaner #9, the user should be instructed afterwards to perform a git-gc afterwards to free up disk space

[OpenBagTwo]

Note that this functionality is going to be largely cosmetic, as libgit2 doesn't actually have functionality to delete or repack objects. See: #9 (comment)

It's worth noting that this functionality is not available in the underlying library: libgit2/libgit2#3247

so it would need to rely on the standalone git executable being available.

Still worth doing--worst case, we should add instructions to perform a git gc manually, in lieu / in advance of #9.

[OpenBagTwo]

Updated the OP, having rethought the UX/UI and understanding better what implementation is actually possible via libgit2.