XML comment crefs unusable with shared/duplicate CsWin32

XML comment `cref`s don't resolve the same way code does. They have visibility to everything, which prevents us from using them when we have duplicate type names in dependent assemblies or types that cross assemblies. We either have to turn off [CS1574](https://learn.microsoft.com/dotnet/csharp/misc/cs1574) and [CS1580](https://learn.microsoft.com/dotnet/csharp/misc/cs1574), or remove lots of existing `cref`s.

https://github.com/dotnet/winforms/pull/10320#issuecomment-1858617614