refactor: change configuration to system

system/shared/nixpkgs.nix

@@ -0,0 +1,7 @@
+{ }: {
+  config = {
+    allowUnfree = true;
+  };
+
+  overlays = [ (import ./overlays.nix) ];
+}

system/shared/overlays.nix

@@ -0,0 +1,73 @@
+self: super: {
+  customVim = with self; {
+    vim-astro = pkgs.vimUtils.buildVimPlugin {
+      name = "vim-astro";
+      src = pkgs.fetchFromGitHub {
+        owner = "wuelnerdotexe";
+        repo = "vim-astro";
+        rev = "main";
+        sha256 = "HyQ4i/T1uQmGurBqCpo8+ESVSVPsTrLQBxLe2OEYjcY=";
+      };
+    };
+
+    vim-heritage = pkgs.vimUtils.buildVimPlugin {
+      name = "vim-heritage";
+      src = pkgs.fetchFromGitHub {
+        owner = "jessarcher";
+        repo = "vim-heritage";
+        rev = "cffa05c78c0991c998adc4504d761b3068547db6";
+        sha256 = "Lebe5V1XFxn4kSZ+ImZ69Vst9Nbc0N7eA9IzOCijFS0=";
+      };
+    };
+
+    vim-just = pkgs.vimUtils.buildVimPlugin {
+      name = "vim-just";
+      src = pkgs.fetchFromGitHub {
+        owner = "NoahTheDuke";
+        repo = "vim-just";
+        rev = "838c9096d4c5d64d1000a6442a358746324c2123";
+        sha256 = "51b8PxyKqBdeIvmmZyF2hpMBjkyrlZDdTB1opr5JZ7Y=";
+      };
+    };
+
+    vim-textobj-xmlattr = pkgs.vimUtils.buildVimPlugin {
+      name = "vim-textobj-xmlattr";
+      src = pkgs.fetchFromGitHub {
+        owner = "whatyouhide";
+        repo = "vim-textobj-xmlattr";
+        rev = "694a297f1d75fd527e87da9769f3c6519a87ebb1";
+        sha256 = "+91FVP95oh00flINdltqx6qJuijYo56tHIh3J098G2Q=";
+      };
+    };
+
+    tabline-vim = pkgs.vimUtils.buildVimPlugin {
+      name = "tabline-vim";
+      src = pkgs.fetchFromGitHub {
+        owner = "mkitt";
+        repo = "tabline.vim";
+        rev = "69c9698a3240860adaba93615f44778a9ab724b4";
+        sha256 = "51b8PxyKqBdeIvmmZyF2hpMBjkyrlZDdTB1opr5JZ7Y=";
+      };
+    };
+
+    vim-caser = pkgs.vimUtils.buildVimPlugin {
+      name = "vim-caser";
+      src = pkgs.fetchFromGitHub {
+        owner = "arthurxavierx";
+        repo = "vim-caser";
+        rev = "master";
+        sha256 = "PXAY01O/cHvAdWx3V/pyWFeiV5qJGvLcAKhl5DQc0Ps=";
+      };
+    };
+
+    vim-visual-star-search = pkgs.vimUtils.buildVimPlugin {
+      name = "vim-visual-star-search";
+      src = pkgs.fetchFromGitHub {
+        owner = "nelstrom";
+        repo = "vim-visual-star-search";
+        rev = "37259722f45996733fd309add61385a4ad88bdb9";
+        sha256 = "n8jd6fy30XukZ9NFZX5qclSlMfziP/Ew9dXfkysRl4Y=";
+      };
+    };
+  };
+}