The argument viAlias mimicks the behavior of vimAlias: when set to true, it
creates a symbolic link from $out/bin/vi to $out/bin/nvim.

Motivation for this change

It is likely that the user that sets vimAlias to true does not have vim installed. In this case, using viAlias allows them to get a "vi" back.

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option build-use-sandbox in nix.conf on non-NixOS)
• 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 nox --run "nox-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Fits CONTRIBUTING.md.