Added contributor classes for manga. Implemented MangaDex search.

MangaReader.Core/Data/MangaContributor.cs

@@ -0,0 +1,12 @@
+namespace MangaReader.Core.Data;
+
+public class MangaContributor
+{
+    public int MangaId { get; set; }
+    public required Manga Manga { get; set; }
+
+    public int ContributorId { get; set; }
+    public required Contributor Contributor { get; set; }
+
+    public MangaContributorRole Role { get; set; }
+}