[early|draft] Enable HiDPI support

[ThatStella7922]

This PR aims to enable HiDPI support. At first glance, it works, running on macOS 12.0.1 on M1 Max.

There are some issues that need to be fixed though:

• [ ] Mouse positioning breaks
• [ ] window scaling can be weird across monitors
• [ ] If HiDPI, ImGui should automatically scale so its shown at a proper legible size without the user configuring it for 2x or whatever
• [ ] Test on platforms other than macOS

These are things above my skill level (c++) for now, so I am going to leave this draft here just for others to see.

[k4zmu2a]

What are the benefits of adding DPI support for this game? To me, it seems like scaling by OS as non-DPI aware program should be good enough.

[kowalski7cc]

Even if the patch makes menus text less blurry, they get really small (at least on Linux with hidpi)