Merge branch 'nd/worktree-lock'

"git worktree prune" protected worktrees that are marked as "locked" by creating a file in a known location. "git worktree" command learned a dedicated command pair to create and remove such a file, so that the users do not have to do this with editor. * nd/worktree-lock: worktree.c: find_worktree() search by path suffix worktree: add "unlock" command worktree: add "lock" command worktree.c: add is_worktree_locked() worktree.c: add is_main_worktree() worktree.c: add find_worktree()