treewide: Use nixpkgs fetchers for npins

plugins: switch from neodev to lazydev

lib/stdlib-extended.nix

@@ -1,6 +1,10 @@
 # Convenience function that returns the given Nixpkgs standard library
 # extended with our functions using `lib.extend`.
-inputs:
+{
+  inputs,
+  self,
+  ...
+} @ args:
 inputs.nixpkgs.lib.extend (self: super: {
   # WARNING: New functions should not be added here, but to files
   # imported by `./default.nix` under their own categories. If your
@@ -12,7 +16,7 @@ inputs.nixpkgs.lib.extend (self: super: {
   # E.g. for an input called `nvf`, `inputs.nvf.lib.nvim` will return the set
   # below.
   nvim = import ./. {
-    inherit inputs;
+    inherit (args) inputs self;
     lib = self;
   };