Add install hook subcommand

It would be nice if we could do `git-worktreeinclude install` that would add a git hook ([example1](https://mskelton.dev/bytes/20230906143340) [example 2](https://github.com/keithamus/git-worktree-share/blob/main/bin/git-worktree-share#L167)) so that when a new worktree is created, it automatically applies the `.worktreeinclude` file.

