refactor: add common mixin standard app widgets

lib/widgets/common.dart

@@ -0,0 +1,33 @@
+import 'package:flutter/material.dart';
+import '../config/strings/app_strings.dart';
+
+mixin StandardAppWidgets {
+  void showAboutDialogWidget(
+      BuildContext context, MediaQueryData mediaQuery, ThemeData theme) {
+    return showAboutDialog(
+      context: context,
+      applicationName: AppString.kAppName,
+      applicationVersion: AppString.kAppVersion,
+      applicationIcon: Image.asset(
+        'assets/images/logo.png',
+        width: mediaQuery.size.width / 5,
+      ),
+      children: [
+        Text(
+          AppString.kCopyrightStatement,
+          style: theme.textTheme.labelMedium,
+        ),
+      ],
+    );
+  }
+
+  void showSnackBarWidget(BuildContext context, String message,
+      {Color? color}) {
+    ScaffoldMessenger.of(context).showSnackBar(
+      SnackBar(
+        content: Text(message),
+        backgroundColor: color,
+      ),
+    );
+  }
+}