Add support for high DPI display rendering

[ensisoft]

Add support for high DPI display scaling.

What this means.

• rendering resolution and render target size are no longer the same as the display/presentation size.

• the display window can be scaled either manually or by the underlying platform.

• the content rendered by the engine needs to be displayed with some scaling factor/mechanism

  • render to a offscreen render target and then rescale and resample in order to display in the window
  • maintain aspect ratio or stretch
  • platforms (such as Windows) can do some up scaling automatically (probably not ideal results)

• need engine config flags to define the setting for hdpi

• need runtime game accessible way to access the hdpi display scale factor

• need runtime mechanism for letting the game to adjust the hdpi display scale factor

Also applies to fullscreen not just windowed mode.

[ensisoft]

Currently the windows native game host application is DPI "unaware". When the application runs Windows does content scaling automatically (at least in the windowed mode).

https://learn.microsoft.com/en-us/windows/win32/hidpi/high-dpi-desktop-application-development-on-windows#display-scale-factor--dpi