add new struct definitions

Il2CppInspector.Common/Next/Metadata/Il2CppMetadataRange.cs

@@ -0,0 +1,10 @@
+using VersionedSerialization.Attributes;
+
+namespace Il2CppInspector.Next.Metadata;
+
+[VersionedStruct]
+public partial struct Il2CppMetadataRange
+{
+    public int Start { get; private set; }
+    public int Length { get; private set; }
+}