Handle prime-select unknown

[Era-Dorta]

Under certain error conditions prime-select query might return unknown rather than nvidia or intel. It'd be nice to have that case included, with a custom icon so that the user knows that something is wrong.

[andrebrait]

It was in the plans. I ended up forgetting to add this option (it would be a '?' icon or something like that). I'll mark this as a request for improvement :)

[Era-Dorta]

Thanks, a reproducible way to get the unknown status is to active secure boot.
Which by the way makes the readme a bit misleading, the nvidia drivers do work with secure boot, but only after the modules have been signed

[andrebrait]

@Garoe I'll add an icon for Unknown then. Will do as soon as I can. This December is being an unusually busy month for me.

Also, thanks for the information. I knew why the NVIDIA drivers wouldn't work but I had no idea one could sign them!

[mmhobi7]

#28