Referencing MsaAuthenticationProvider throws compiler errors with Project Reunion 0.5 desktop applications

[gcaughey]

Here's the original bug report for Project Reunion https://github.com/microsoft/microsoft-ui-xaml/issues/4526#issuecomment-799691079

The compiler error message indicates an incorrect reference to a Windows.Forms package. Note that this is only an issue for Project Reunion 0.5 desktop running on Win32 and not an issue for Project Reunion 0.5 running on UWP.