Fix: Update URL launch method to use Uri.parse (#12518)

Fixes #12410 

**Before:**
- Wasn't opening the website by clicking on the launch button. I don't
have a screenshot of that as the app was not breaking but was just not
opening the webpage. I could not find any error logs in the emulator
logs. Only thing I can verify is that this issue persists on macOS and iPhone 14 emulator.

**After:**
Opened the website successfully
<img width="382" alt="image"
src="https://github.com/user-attachments/assets/455279e2-b1f5-4d5b-b50c-fef7b4521ab5"
/>

Author: dixita0607

examples/platform_integration/plugin_api_migration/lib/url_launcher.dart

@@ -1,6 +1,5 @@
 // #docregion url-launcher
 import 'package:flutter/material.dart';
-import 'package:path/path.dart' as p;
 import 'package:url_launcher/url_launcher.dart';
 
 void main() {
@@ -20,7 +19,7 @@ class DemoPage extends StatelessWidget {
   const DemoPage({super.key});
 
   void launchURL() {
-    launchUrl(p.toUri('https://flutter.dev'));
+    launchUrl(Uri.parse('https://flutter.dev'));
   }
 
   @override

src/content/packages-and-plugins/using-packages.md

@@ -452,7 +452,6 @@ To use this plugin:
     <?code-excerpt "lib/url_launcher.dart (url-launcher)"?>
     ```dart
     import 'package:flutter/material.dart';
-    import 'package:path/path.dart' as p;
     import 'package:url_launcher/url_launcher.dart';
     
     void main() {
@@ -472,7 +471,7 @@ To use this plugin:
       const DemoPage({super.key});
     
       void launchURL() {
-        launchUrl(p.toUri('https://flutter.dev'));
+        launchUrl(Uri.parse('https://flutter.dev'));
       }
     
       @override