feat: Working VoIP calling implementation (Flutter + Android)

Working video and audio calls, as well as android integration

lib/liblinphone_flutter_platform_interface.dart

@@ -0,0 +1,80 @@
+import 'package:liblinphone_flutter/models/call_type.dart';
+import 'package:plugin_platform_interface/plugin_platform_interface.dart';
+
+import 'liblinphone_flutter_method_channel.dart';
+
+abstract class LiblinphoneFlutterPlatform extends PlatformInterface {
+  /// Constructs a LiblinphoneFlutterPlatform.
+  LiblinphoneFlutterPlatform() : super(token: _token);
+
+  static final Object _token = Object();
+
+  static LiblinphoneFlutterPlatform _instance =
+      MethodChannelLiblinphoneFlutter();
+
+  /// The default instance of [LiblinphoneFlutterPlatform] to use.
+  ///
+  /// Defaults to [MethodChannelLiblinphoneFlutter].
+  static LiblinphoneFlutterPlatform get instance => _instance;
+
+  /// Platform-specific implementations should set this with their own
+  /// platform-specific class that extends [LiblinphoneFlutterPlatform] when
+  /// they register themselves.
+  static set instance(LiblinphoneFlutterPlatform instance) {
+    PlatformInterface.verifyToken(instance, _token);
+    _instance = instance;
+  }
+
+  Future<bool> checkPermissions() {
+    throw UnimplementedError('checkPermissions() has not been implemented.');
+  }
+
+  Future<bool> initialize() {
+    throw UnimplementedError('initialize() has not been implemented.');
+  }
+
+  Future<bool> register(
+    String username,
+    String password,
+    String serverIp,
+    int serverPort,
+  ) {
+    throw UnimplementedError('register() has not been implemented.');
+  }
+
+  Future<bool> unregister() {
+    throw UnimplementedError('unregister() has not been implemented.');
+  }
+
+  Future<bool> makeCall(String callTo, bool isVideoEnabled) {
+    throw UnimplementedError('makeCall() has not been implemented.');
+  }
+
+  Future<bool> answerCall() {
+    throw UnimplementedError('answerCall() has not been implemented.');
+  }
+
+  Future<bool> hangupCall() {
+    throw UnimplementedError('hangupCall() has not been implemented.');
+  }
+
+  Future<bool> inCall() {
+    throw UnimplementedError('inCall() has not been implemented.');
+  }
+
+  Future<CallType> callType() {
+    throw UnimplementedError('callType() has not been implemented.');
+  }
+
+  Future<bool> toggleVideo() {
+    throw UnimplementedError('toggleVideo() has not been implemented.');
+  }
+
+  Future<bool> toggleMicrophone() {
+    throw UnimplementedError('toggleMicrophone() has not been implemented.');
+  }
+
+  Future<bool> stop() {
+    throw UnimplementedError('stop() has not been implemented.');
+  }
+}