Linkit shows unpublished media in matcher

Working on it.

As a maintainer, I would note that if we change the default behavior not to show unpublished media, this would effectively change users' expectations on existing sites. A content editor used to seeing unpublished media items would no longer see them. Is that reasonable? I'm not necessarily saying that we should implement this as an "opt out" feature (i.e., an option to hide unpublished media entities), but if we do this, I think we need to call this out loudly in the release notes and documentation as a behavioral change.

This thinking might also suggest that the issue would better be characterized as an enhancment/feature, rather than a bug, since the module was originally created at a time when media entities _couldn't_ have a published state, and was not designed to suppress them.

@mark_fullmer would you accept the current approach in the MR? In the update hook I'm seeing the include_unpublished key to TRUE so existing behavior should be maintained. Any new matchers people add will default to FALSE.