nixos: hardware.nvidia.package option for selecting nvidia package

[eadwu]

Make it possible to select a derivation to use. This also moves some
logic that belongs to the derivation back into it.

Motivation for this change

#49703 upkeep

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS linux)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.

[emmanuelrosa]

I think this should be accompanied with documentation of what the end-user needs to change.

For instance, if the user has something like:

services.xserver.videoDrivers = [ "nvidiaBeta" ];

Meaning, the driver is not simply "nvidia", then it needs to be changed to "nvidia" and then the following needs to be added:

hardware.nvidia.package = config.boot.kernelPackages.nvidiaPackages.beta;

Of course the documentation should be written more elegantly, but that's the gist of it.

[ncfavier]

Don't forget to update the manual:

nixpkgs/nixos/doc/manual/configuration/x-windows.xml

Lines 147 to 153 in a0b7bd6

	</programlisting>
	Or if you have an older card, you may have to use one of the legacy drivers:
	<programlisting>
	<xref linkend="opt-services.xserver.videoDrivers"/> = [ "nvidiaLegacy390" ];
	<xref linkend="opt-services.xserver.videoDrivers"/> = [ "nvidiaLegacy340" ];
	<xref linkend="opt-services.xserver.videoDrivers"/> = [ "nvidiaLegacy304" ];
	</programlisting>

And the example for services.xserver.videoDrivers:

nixpkgs/nixos/modules/services/x11/xserver.nix

Line 255 in a0b7bd6

"nvidia" "nvidiaLegacy390" "nvidiaLegacy340" "nvidiaLegacy304"