Enable PROTON_USE_WINED3D=1 for Box32
Since Box32 does not wrap 32-bit Vulkan libraries yet, is it possible to set the environment variable `PROTON_USE_WINED3D=1` for Box32 only (not Box64 since Vulkan works for 64-bit games)?

For example, I may run Steam which uses Box64 and Box32. Then I'll install various games. If I launch a 64-bit game, I want it to use DXVK so it uses Vulkan for the best DirectX translation. If I launch a 32-bit game, I want it to use WineD3D so it uses OpenGL for the best/only Box32 translation.

Today, I'm simply using the Steam launch argument `PROTON_USE_WINED3D=1 %command%` for all of my old games. I was curious if it was possible to automate this within Box32.