Tech Debt + Series Sort bugfix (#1192)

* Code cleanup.

When copying files, if the target file already exists, append (1), (2), etc onto the file (this is enhancing existing implementation to allow multiple numbers)

* Added a ton of null checks to UpdateSeriesMetadata and made the code work on the rare case (not really possible) that SeriesMetadata doesn't exist.

* Updated Genre code to use strings to ensure a better, more fault tolerant update experience.

* More cleanup on the codebase

* Fixed a bug where Series SortName was getting emptied on file scan

* Fixed a bad copy

* Fixed unit tests

API/SignalR/SignalRMessage.cs

@@ -34,6 +34,6 @@ namespace API.SignalR
         /// <summary>
         /// When event took place
         /// </summary>
-        public DateTime EventTime = DateTime.Now;
+        public readonly DateTime EventTime = DateTime.Now;
     }
 }