ScummVM: Implement High DPI Scaling Warnings for Windows Users

[CTxCB]

Starting from v2.1.0, I'd like ScummVM to check if the user's executable is set to allow the Application (instead of System) to override High DPI Scaling Behaviour in Windows, if that's possible to even check via code? And for those that aren't, to put a Warning Message in the Status Window, suggesting that they do so. I'm unsure if other Operating Systems use any similar techniques, but if so, it might be a good idea to implement similar Warning Messages for those too.

I've included example screenshots from a range of different SCI0 games to highlight the issue, with ScummVM running in both System and Application High DPI Scaling, I hope you'll agree that ScummVM suffers noticeable graphics issues when High DPI Scaling is set to System instead of Application (and this becomes especially noticeable when playing games in fullscreen); I believe most users would benefit from such a Warning Message.

[lotharsm]

I'm currently working on this feature. I already figured out how we can check if we are running at HiDPI using the proper SDL2 callbacks. I can't give an ETA for this feature yet, but I'm looking at it.