Add a "creates" state, to create a file without spurious 'changed'

This permit to be used with this pattern :

    - file:
        path: "/srv/git/{{ item.name }}/git-daemon-export-ok"
        state: "{% if item.private %}absent{% else %}creates{% endif %}"
      with_items: git_repositories

And git_repositories being a array of item with a member "private".
Using copy/template would requires to used 2 actions instead
of 1, with duplication.