git-clean: new interactive action: select by numbers

Draw a multiple choice menu using `list_and_choose` to select items
to be deleted.

User can input:

 * `*`     : select all items to be deleted
 * `-*`    : unselect all, nothing will be deleted
 * `1,3-5` : select 1,3,4,5 items to be deleted
 *         : (empty) finish selecting, and return back to main menu

Signed-off-by: Jiang Xin <worldhello.net@gmail.com>