Support for TraktTV in WebUI

[TheOne320]

As Shoko Desktop will be phased out in the future, there has to be a way to manually link and unlink to TraktTV using the WebUI. This currently does not exist.

[ElementalCrisis]

@revam if the API exists, I can look at mocking something up. It shouldn't be too hard since Trakt is just a single link as opposed to TMDB linking.

[da3dsoul]

We used to have TvDB to Trakt. It's probably worth looking into if we can do the same for TMDB

[revam]

@da3dsoul in the current stable it's linked against TvDB. But in the current daily it's linked against TMDB.

It might need some hard love (read as; refactoring) internally before we add APIv3 models and endponts though. No idea. Haven't really looked closely at it yet.