Restructure flake.nix for a simpler config for building different images off the same NixOS config.

nix/configuration/util/install_files/default.nix

@@ -1,7 +1,6 @@
 {
   config,
   lib,
-  pkgs,
   ...
 }:
 
@@ -309,25 +308,23 @@ in
           Type = "oneshot";
           RemainAfterExit = "yes";
         };
-        script =
-          ''
-            set -o pipefail
-            IFS=$'\n\t'
-            source ${./files/lib.bash}
-          ''
-          + (lib.strings.concatStringsSep "\n" (
-            [
-            ]
-            ++ check_commands
-            ++ install_commands
-          ));
-        preStop =
-          ''
-            set -o pipefail
-            IFS=$'\n\t'
-            source ${./files/lib.bash}
-          ''
-          + (lib.strings.concatStringsSep "\n" uninstall_commands);
+        script = ''
+          set -o pipefail
+          IFS=$'\n\t'
+          source ${./files/lib.bash}
+        ''
+        + (lib.strings.concatStringsSep "\n" (
+          [
+          ]
+          ++ check_commands
+          ++ install_commands
+        ));
+        preStop = ''
+          set -o pipefail
+          IFS=$'\n\t'
+          source ${./files/lib.bash}
+        ''
+        + (lib.strings.concatStringsSep "\n" uninstall_commands);
       };
     };
 }