popn: allow game to launch on PCs with only one monitor (#633)

## Link to GitHub Issue or related Pull Request, if one exists
#618 

## Description of change
The game insists on having two monitors. Hook various DX9 and Win32
monitor APIs to fake a monitor if the user only has one. This correctly
convinces the game that it needs to draw two screens instead of just
one.

## Testing
WIP

src/spice2x/hooks/graphics/graphics.cpp

@@ -40,6 +40,7 @@ HWND TDJ_SUBSCREEN_WINDOW = nullptr;
 HWND SDVX_SUBSCREEN_WINDOW = nullptr;
 HWND GFDM_SUBSCREEN_WINDOW = nullptr;
 HWND POPN_SUBSCREEN_WINDOW = nullptr;
+bool FAKE_SUBSCREEN_ADAPTER = false;
 
 // icon
 static HICON WINDOW_ICON = LoadIcon(GetModuleHandle(nullptr), MAKEINTRESOURCE(MAINICON));