Copy ctor handling for crossgen2 (#40113)

Copy ctor handling for crossgen2 (#40113)

- Add IL based test for copy ctor to allow testing in Crossgen2 which doesn't yet support IJW
- Add api to determine proper EmbeddedSignatureData index for these
  - And tests to ensure this remains functional
- Marshaller changes to recognize copy constructor cases
  - Note that there isn't actual marshaller support. Instead the compiler can now able to detect when copy ctors should be used, and falls back to the runtime interop layer