feat: Working VoIP calling implementation (Flutter + Android)

Working video and audio calls, as well as android integration

example/lib/main.dart

@@ -0,0 +1,63 @@
+import 'package:flutter/material.dart';
+import 'dart:async';
+
+import 'package:flutter/services.dart';
+import 'package:liblinphone_flutter/liblinphone_flutter.dart';
+
+void main() {
+  runApp(const MyApp());
+}
+
+class MyApp extends StatefulWidget {
+  const MyApp({super.key});
+
+  @override
+  State<MyApp> createState() => _MyAppState();
+}
+
+class _MyAppState extends State<MyApp> {
+  String _platformVersion = 'Unknown';
+  final _liblinphoneFlutterPlugin = LiblinphoneFlutter();
+
+  @override
+  void initState() {
+    super.initState();
+    initPlatformState();
+  }
+
+  // Platform messages are asynchronous, so we initialize in an async method.
+  Future<void> initPlatformState() async {
+    String platformVersion;
+    // Platform messages may fail, so we use a try/catch PlatformException.
+    // We also handle the message potentially returning null.
+    try {
+      platformVersion =
+          await _liblinphoneFlutterPlugin.getPlatformVersion() ?? 'Unknown platform version';
+    } on PlatformException {
+      platformVersion = 'Failed to get platform version.';
+    }
+
+    // If the widget was removed from the tree while the asynchronous platform
+    // message was in flight, we want to discard the reply rather than calling
+    // setState to update our non-existent appearance.
+    if (!mounted) return;
+
+    setState(() {
+      _platformVersion = platformVersion;
+    });
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return MaterialApp(
+      home: Scaffold(
+        appBar: AppBar(
+          title: const Text('Plugin example app'),
+        ),
+        body: Center(
+          child: Text('Running on: $_platformVersion\n'),
+        ),
+      ),
+    );
+  }
+}