flake.nix: refactoring using flake-parts

flake-modules/modules.nix

@@ -0,0 +1,47 @@
+{
+  modules,
+  inputs,
+  ...
+}: {
+  _module.args = let
+    nixvimModules = with builtins;
+      map
+      (f: ../modules + "/${f}")
+      (
+        attrNames (readDir ../modules)
+      );
+  in {
+    modules = pkgs: let
+      nixpkgsMaintainersList = pkgs.path + "/nixos/modules/misc/meta.nix";
+
+      nixvimExtraArgsModule = rec {
+        _file = ./flake.nix;
+        key = _file;
+        config = {
+          _module.args = {
+            pkgs = pkgs.lib.mkForce pkgs;
+            inherit (pkgs) lib;
+            helpers = import ../lib/helpers.nix {inherit (pkgs) lib;};
+            # TODO: Not sure why the modules need to access the whole flake inputs...
+            inherit inputs;
+          };
+        };
+      };
+    in
+      nixvimModules
+      ++ [
+        nixpkgsMaintainersList
+        nixvimExtraArgsModule
+      ];
+  };
+
+  perSystem = {
+    pkgs,
+    config,
+    ...
+  }: {
+    _module.args = {
+      modules = modules pkgs;
+    };
+  };
+}