Display monitor selector

[jasaaved]

Summary:

• Adds a "Display Monitor" dropdown to Graphics > General, allowing users to select which monitor to launch the game on
• In fullscreen mode, the game launches fullscreen on the selected monitor
• In windowed mode, the render window (or main window when rendering to main) is centered on the selected monitor
• When rendering to the main window, the main window is moved to the selected monitor and restored to its original position when the game ends

Test plan:

• Single monitor: verify default behavior is unchanged
• Multi-monitor: verify fullscreen launches on the selected monitor
• Multi-monitor: verify windowed separate window centers on the selected monitor
• Multi-monitor, render to main window: verify the main window moves to the selected monitor when the game starts and restores to its original
  position when the game ends
• Multi-monitor, render to main window: verify that if the main window is already on the selected monitor, it does not move
• Multi-monitor, separate window: verify that exiting fullscreen restores the window to its pre-fullscreen position rather than re-centering it on the selected monitor
• Verify "Default Monitor" (index 0) behaves identically to previous behavior

[jordan-woyak]

When Render to Main is turned off the window position isn't restored upon return from fullscreen on a secondary monitor which is a bit odd/annoying.

I think "Primary Monitor" might not be the correct description. Maybe just call it "Default" ?

[jasaaved]

The position will now restore when exiting from fullscreen so it won't recenter. I changed it to "Default Monitor" as well.