Having both GL and GL32 extension results in duplicated Vulkan nvidia_icd.json files

Hi there,

I have a standard Fedora 36 installation with NVIDIA drivers installed (x64 and i686 libraries installed) and both the `GL` and `GL32` flatpak application installed. Running `vulkaninfo` on the host shows a single GPU which matches reality. When running a Vulkan application inside flatpak however, the application sees the same device twice.

I'm not familiar how the driver setup in flatpak works, but this looks very similar to https://github.com/negativo17/nvidia-driver/issues/95 where both the x64 and i686 nvidia driver put an Vulkan icd file with the same content into `/usr/share/vulkan/icd.d/` which made Vulkan to load the same device twice. So my completely uneducated guess would be that this lines https://github.com/flathub/org.freedesktop.Platform.GL.nvidia/blob/master/nvidia-apply-extra.c#L112 and https://github.com/flathub/org.freedesktop.Platform.GL.nvidia/blob/master/nvidia-apply-extra.c#L463 (probably also https://github.com/flathub/org.freedesktop.Platform.GL.nvidia/blob/master/nvidia-apply-extra.c#L117) should only apply to the GL/x64 driver package. I could be wrong though.

Kind regards and thanks a lot for all your hard work!