Album gain (#10085)

* Add LUFSAlbum DTO

* Get loudest track for smallest gain

* Move gain search to musicalbum
use baseitem LUFS for album

* Use .Max for enumerable

* Update DTO to be consistent with other DTOs

* Remove albumlufs,
Move dto for all types

Emby.Server.Implementations/Dto/DtoService.cs

@@ -903,10 +903,11 @@ namespace Emby.Server.Implementations.Dto
                 dto.IsPlaceHolder = supportsPlaceHolders.IsPlaceHolder;
             }
 
+            dto.LUFS = item.LUFS;
+
             // Add audio info
             if (item is Audio audio)
             {
-                dto.LUFS = audio.LUFS;
                 dto.Album = audio.Album;
                 if (audio.ExtraType.HasValue)
                 {

MediaBrowser.Controller/Entities/Audio/MusicAlbum.cs

@@ -183,6 +183,9 @@ namespace MediaBrowser.Controller.Entities.Audio
                 progress.Report(percent * 95);
             }
 
+            // get album LUFS
+            LUFS = items.OfType<Audio>().Max(item => item.LUFS);
+
             var parentRefreshOptions = refreshOptions;
             if (childUpdateType > ItemUpdateType.None)
             {