feat(stacked-diffs): add --no-verify to 'stack amend' command

Description

Similar to glab stack save in !3387 (merged), this adds a --no-verify command to the glab stack amend command, so glab skips hooks (such as pre-commit or or lefthook).

This shouldn't be part of the default workflow but can save time when just comitting e.g. a comment-only change.

Related Issues

None.

How has this been tested?

Yes, by passing --no-verify to glab stack amend.