Implemented Article: Add article to series

As mentioned in this thread (Updated - Series: Several misc updates), Update #4: Article Owners can now add their Article to a Series directly from the Article itself instead of having to navigate to the series just to add an article to it.

I've added a new feature to Articles that allow articles to be added to a series directly from the Article page itself.

If the viewing user has permission to add the Article to a series in general, whether it be one of their own or a community series, and the article is not currently in a series already, the viewing user will see a new button [Add to series] as shown below.




Clicking on the [Add to series] button will launch a form in an overlay as shown below.

There are 3 different options to choose from.

• The first one is based on the viewing user. This will fetch all series that are owned or managed by the viewing user.
• The second one fetches all community series IF the viewing user has global permission to post articles in community series.
• The 3rd one is mainly for staff, which allows them to set a Series that they don't own, but are allowed to add articles to because they are staff.