add VersionedSerialization + source generator

VersionedSerialization/IReadable.cs

@@ -0,0 +1,7 @@
+namespace VersionedSerialization;
+
+public interface IReadable
+{
+    public void Read<TReader>(ref TReader reader, in StructVersion version = default) where TReader : IReader, allows ref struct;
+    public static abstract int Size(in StructVersion version = default, bool is32Bit = false);
+}