Added abstraction layeer IHtmlLoader. Finished reorganizing test project folder structure.

MangaReader.Core/Data/MangaTitle.cs

@@ -1,4 +1,6 @@
-namespace MangaReader.Core.Data;
+using MangaReader.Core.Common;
+
+namespace MangaReader.Core.Data;
 
 public class MangaTitle
 {
@@ -8,5 +10,6 @@ public class MangaTitle
     public required Manga Manga { get; set; }
 
     public required string Name { get; set; }
-    public TitleType TitleType { get; set; }
+    public required Language Language { get; set; }
+    public bool IsPrimary { get; set; }
 }