refactor(newsletter): ♻️ Media servers + newsletter refactoring (#4463)

* Abstract media servers content into interfaces

* Media server entities into abstract classes

* Abstract media server content repository

* First pass at newsletter refactoring

* Minor code clean up

* Attempt at abstracting repositories (WIP)

* Fixed cast issue

* Corrected the other properties

* A step towards newsletter refactoring

* Clean up leftovers

* Fix broken episodes db interaction

* Save absolute URL for Plex content

Let's be consistent with Emby and Jellyfin

* Fix broken integration with Plex libraries

* Fix error when multiple media servers configured

* Fix newsletter being sent if no movies or episodes

* Fix broken tests

* Remove unneccesary logs

* Expose stored media server URL

No need to recalculate it
+ Plex URL was broken due to an earlier change

* Remove unused variable

* Remove obsolete tests

URLs are now fetched from database directly

* Retro-compatibility for Plex content URL

Solves URL for media synced before absolute URL was saved in PlexServerContent

* chore: added some obsoletes

* fix: removed the unsub link when not present

Co-authored-by: tidusjar <tidusjar@gmail.com>

src/Ombi.Helpers/PlexHelper.cs

@@ -104,11 +104,11 @@ namespace Ombi.Helpers
             return new ProviderId();
         }
 
-        public static string GetPlexMediaUrl(string machineId, int mediaId)
+        public static string GetPlexMediaUrl(string machineId, int mediaId, string plexHost)
         {
             var url =
                 $"web/#!/server/{machineId}/details?key=%2flibrary%2Fmetadata%2F{mediaId}";
-            return url;
+            return BuildPlexMediaUrl(url, plexHost);
         }
 
         public static string BuildPlexMediaUrl(string savedUrl, string plexHost)