Added contributor classes for manga. Implemented MangaDex search.

MangaReader.Core/Search/MangaSearchResult.cs

@@ -5,6 +5,7 @@ public record MangaSearchResult
     public required string Source { get; init; }
     public required string Url { get; init; }
     public required string Title { get; init; }
+    public string? Thumbnail { get; init; }
     public string? Author { get; init; }
     public string? Description { get; init; }
 }