Clean up common user modules

Signed-off-by: Nikolaos Karaolidis <nick@karaolidis.com>

users/configs/neovim/default.nix

@@ -0,0 +1,19 @@
+{ user ? throw "user argument is required" }: { ... }:
+
+{
+  home-manager.users."${user.name}" = {
+    programs.neovim = {
+      enable = true;
+      defaultEditor = true;
+      viAlias = true;
+      vimAlias = true;
+      vimdiffAlias = true;
+      extraConfig = ''
+        set tabstop=2
+        set shiftwidth=2
+        set expandtab
+        set smartindent
+      '';
+    };
+  };
+}