refactor: move dialog to widgets

lib/widgets/dialog_about.dart

@@ -0,0 +1,29 @@
+import 'package:apidash/consts.dart';
+import 'package:flutter/material.dart';
+import 'package:apidash/widgets/widgets.dart';
+
+showAboutAppDialog(
+  BuildContext context,
+) {
+  showDialog(
+      context: context,
+      builder: (context) {
+        return AlertDialog(
+          contentPadding: kPt20 + kPh20 + kPb10,
+          content: Container(
+            width: double.infinity,
+            height: double.infinity,
+            constraints: const BoxConstraints(maxWidth: 540, maxHeight: 544),
+            child: const IntroMessage(),
+          ),
+          actions: [
+            TextButton(
+              onPressed: () {
+                Navigator.of(context).pop();
+              },
+              child: const Text("Close"),
+            ),
+          ],
+        );
+      });
+}

lib/widgets/widgets.dart

@@ -10,7 +10,8 @@ export 'card_sidebar_request.dart';
 export 'checkbox.dart';
 export 'code_previewer.dart';
 export 'codegen_previewer.dart';
-export 'dialogs.dart';
+export 'dialog_about.dart';
+export 'dialog_rename.dart';
 export 'dropdown_codegen.dart';
 export 'dropdown_content_type.dart';
 export 'dropdown_formdata.dart';