Support scrollable windows (WS_{H,V}SCROLL) on Windows

[pkasting]

Description

Windows allows the WS_HSCROLL and WS_VSCROLL styles (https://learn.microsoft.com/en-us/windows/win32/winmsg/window-styles) for scrollable windows. This would be useful for e.g. terminal emulators.

I don't know how other platforms handle scrolling enough to know whether there's a sane cross-platform abstraction here.

Relevant platforms

Windows