Add NVK as a driver option for nvidia.

[XeZey]

I have tested the driver out recently, and they are surprisingly good, and even give me better perfomance in games like osu lazer! than the proprietary drivers. for some reason, NVK makes the game appear buttery smooth, and it gives the appearance that proprietary drivers actually have some sort of microstuttering (im not sure how accurate this is, but theres definitely something weird going on, and this is true for every game I have played, regardless of how proprietary drivers are set up/configured). I dont think there is a good reason as to why it shouldn't be added to the list of possible drivers at this point in time.