Added MangaDex Api. Updated project structure.

MangaReader.Core/Metadata/MangaWebCrawler.cs

@@ -0,0 +1,18 @@
+using HtmlAgilityPack;
+
+namespace MangaReader.Core.Metadata;
+
+public abstract class MangaWebCrawler : IMangaMetadataProvider
+{
+    public abstract SourceManga GetManga(string url);
+
+    protected virtual HtmlDocument GetHtmlDocument(string url)
+    {
+        HtmlWeb web = new()
+        {
+            UsingCacheIfExists = false
+        };
+
+        return web.Load(url);
+    }
+}