Add New Architecture support for Microsoft.ReactNative.Managed and Microsoft.ReactNative.Managed.Codegen

[jonthysell]

Summary

The current Microsoft.ReactNative.Managed project(s) adds all of the module / view manager "helpers" for C# projects. We will need (some) of those for New Architecture projects.

Motivation

To continue support for C# that we started in the Old Architecture.

Basic Example

No response

Open Questions

No response