Add the errhandlingapi.h methods (SetErrorMode, etc)

[Nicholas Hayes]

I am in the process of converting a .NET 6 project to use TerraFx, and SetErrorMode is the only missing method that I use.

[AraHaan]

After looking at the docs any reason why you prefer SetErrorMode over SetThreadErrorMode?

[Nicholas Hayes]

After looking at the docs any reason why you prefer SetErrorMode over SetThreadErrorMode?

I call SetErrorMode during process startup to prevent the critical error handler dialog from being displayed.
From the SEM_FAILCRITICALERRORS documentation:

Best practice is that all applications call the process-wide SetErrorMode function with a parameter of SEM_FAILCRITICALERRORS at startup. This is to prevent error mode dialogs from hanging the application.