GS/DX11: Don't throw bad_alloc on surface creation fail
GS: Link device and host display construction/destruction
FullscreenUI: Replace HostDisplayTexture with GSTexture
GS: Purge HostDisplayTexture
GS: Move everything in HostDisplay to GSDevice
GS: Move ImGui rendering to GSDevice
GS: Get rid of reset/store API state
Stenzek