Add tvrage and imdb ids for episodes

[cvium]

When I rewrote tmdb providers I probably forgot about the external links on the episode page...

Issues
Fixes #5869

[SenorSmartyPants]

Please also set TMDBId, which TMDB does not consider external, but JF would.

Something like this.

            if (!string.IsNullOrEmpty(episodeResult.Id))
            {
                item.SetProviderId(MetadataProvider.Tmdb, episodeResult.Id);
            }