more local metadata parsing improvements (#776)

* extract remaining nfo xml serializers

* add artist nfo tests

* add music video nfo tests

* add tv show nfo reader tests

* custom artist nfo reader

* custom music video nfo reader

* custom tv show nfo reader

* local metadata parsing cleanup

* update changelog

ErsatzTV.Core/Interfaces/Metadata/Nfo/IArtistNfoReader.cs

@@ -0,0 +1,8 @@
+using ErsatzTV.Core.Metadata.Nfo;
+
+namespace ErsatzTV.Core.Interfaces.Metadata.Nfo;
+
+public interface IArtistNfoReader
+{
+    Task<Either<BaseError, ArtistNfo>> Read(Stream input);
+}

ErsatzTV.Core/Interfaces/Metadata/Nfo/IEpisodeNfoReader.cs

@@ -4,5 +4,5 @@ namespace ErsatzTV.Core.Interfaces.Metadata.Nfo;
 
 public interface IEpisodeNfoReader
 {
-    Task<List<TvShowEpisodeNfo>> Read(Stream input);
+    Task<Either<BaseError, List<TvShowEpisodeNfo>>> Read(Stream input);
 }

ErsatzTV.Core/Interfaces/Metadata/Nfo/IMusicVideoNfoReader.cs

@@ -0,0 +1,8 @@
+using ErsatzTV.Core.Metadata.Nfo;
+
+namespace ErsatzTV.Core.Interfaces.Metadata.Nfo;
+
+public interface IMusicVideoNfoReader
+{
+    Task<Either<BaseError, MusicVideoNfo>> Read(Stream input);
+}

ErsatzTV.Core/Interfaces/Metadata/Nfo/ITvShowNfoReader.cs

@@ -0,0 +1,8 @@
+using ErsatzTV.Core.Metadata.Nfo;
+
+namespace ErsatzTV.Core.Interfaces.Metadata.Nfo;
+
+public interface ITvShowNfoReader
+{
+    Task<Either<BaseError, TvShowNfo>> Read(Stream input);
+}