Bug#875959: vidia-graphics-drivers: port nvidia-prime from Ubuntu

[Vincas Dargis]

I have tried (naively) `nvidia-prime` Ubuntu package installed in Debian Testing, but it does not work:

sudo prime-select nvidia
Info: the current GL alternatives in use are: [None, None]
Info: the current EGL alternatives in use are: [None, None]
Error: the installed packages do not support PRIME
Error: nvidia mode can't be enabled