When DirectX 12 is missing, the emulator thinks Vulkan = DirectX 12 because Vulkan takes DX12's place in the box (id=2), and therefore runs DX12 when Vulkan is selected, crashing the emulator with an unhandled exception.
Fixes it by translating renderer string value to the respective enum class before sending the value to config.h instead of just relying on the box's selected id -> cbox_gs_render->GetSelection()
Also changes the order of the renderers (for convinience, now DX12 is id=3) from
Null, OpenGL, DirectX 12, Vulkan
to
Null, OpenGL, Vulkan, DirectX 12
