Implemented Override the default sort order for the items listing on a specific category

This is a re-implementation of the same feature in SC 2.9. This was a PAID request to be implemented earlier than planned.

As per title, I've added a new category setting to the Category extra options that lets you override the default sort order of the Item listing on a specific category page. This comes in handy for doing things like having a Category that you want to list articles in Alphabetical order when the global default is by "Last Update".

Here you can see that I am overriding the global option (last_update) and setting it to sort by title for this particular category.