C++/WinRT - Support using OneToolkit WinRT APIs by importing the module file

[JaiganeshKumaran]

Moved from Azure Boards. Original creation timestamp: 2022-01-02 21:00 +05:30.

Today, to consume OneToolkit WinRT APIs from C++/WinRT, you've to manually include the generated projection headers. Previously the OneToolkit.h header file included all of them, however, now I'm considering moving away from headers and using modules instead. The problem is that C++/WinRT doesn't yet support consuming projection headers as a module, and since it defines macros, causes too many warnings when you try to export them from a module. Find a way to consume those APIs defined in projection headers directly by importing the module.