Libraries

This change looks dramatic, but it's just separating out the already-split namespaces into separate top-level folders. In theory, every single one could be built into their own Nuget package. `SabreTools.Serialization` still builds the normal Nuget package that is used by all other projects and includes all namespaces.

SabreTools.Data.Models/DosCenter/MetadataFile.cs

@@ -0,0 +1,11 @@
+namespace SabreTools.Data.Models.DosCenter
+{
+    public class MetadataFile
+    {
+        /// <remarks>doscenter</remarks>
+        public DosCenter? DosCenter { get; set; }
+
+        /// <remarks>game</remarks>
+        public Game[]? Game { get; set; }
+    }
+}