Let HLS Controller decide if subtitle should be burn in

Previously, we predicted whether the subtitle should be burned in with transcode reasons, but that was not accurate because the actual transcoding codec is only determined after the client has requested the stream. This pass through the option to the `DynamicHlsController` to handle the subtitle burn-in during the actual transcoding process. Now the client should be responsible to conditionally load the subtitle when this option is enabled.

MediaBrowser.Controller/MediaEncoding/BaseEncodingJobOptions.cs

@@ -193,6 +193,8 @@ namespace MediaBrowser.Controller.MediaEncoding
 
         public bool EnableAudioVbrEncoding { get; set; }
 
+        public bool AlwaysBurnInSubtitleWhenTranscoding { get; set; }
+
         public string GetOption(string qualifier, string name)
         {
             var value = GetOption(qualifier + "-" + name);