Add filter for _post_states as it outputs raw HTML

[brandbrilliance]

Currently this function can't be overridden with a filter, so it outputs raw HTML separators and such directly into the post title in the edit screen. However it should be suggested to make it possible to display the post states in your own custom function, e.g. remove the separators and the divider with the title, which are currently hard-coded at the moment in the function as raw HTML?