This fixes modularization errors that arise when importing a C++ header that contains `#include <guiddef.h>`, which might hijack this header from the WinSDK module where it belongs.
Inject the necessary module maps and apinotes via the VFS. This cleans
up the developer build in preparation for a secondary change to remove
this need for deployed scenarios as well. Injecting the content via the
VFS will enable us restore the ability to work with a pristine
installation of Visual Studio, dropping the custom action for the Swift
installer, and open the pathway to per-user installation of Swift.
Thanks to @bnbarham for the help and discussion in resolving the test
issues.
