Store the driver top-level DSOs to /run/opengl-driver

Idea of @soupglasses We would still modify the rpaths to point to `/var/lib` Pros: - Can use Nix binaries without wrapping them first. - Fixes the wrapper startup overhead. Cons: - Need something to keep `/run/opengl-driver` in sync. - We can do that using the package managers hooks. That means we have to distribute nix-gl-host through the host package manager though. - We can do that using a nix-distributed daemon epolling the top-level DSOs.