Add option to sort by user rating

[Sonphil]

trafficstars

At the moment, on the Collection page, I can sort my shows and my movies by rating. However, I would also like to sort them by my rating (userRating), so something like

USER_RATING -> movies.sortedByDescending { it.userRating }

[michaldrabik]

Yeah It probably makes sense. Just needs some more work to account user not being logged into Trakt or a failure while preloading ratings. I'll take a look.