Implement DXVK option on the Windows Version

[JordonAM]

Much like the title, it would really be nice to see DXVK implementation on the Windows version of Heroic. Some games, especially old ones, benefit a lot from being translated to Vulkan from DX9 or DX11 in performance, i.e. Condemned: Criminal Origins which basically needs DXVK, GTAIV, Fallout NV, Watch Dogs, Metro Last Light and some newer single player games like God of War 2018. Of course, DXVK doesn't work on every game and it would be wise to have a disclaimer for that, but a sort of toggle for it would be nice!