Fix/419 audio preview stop now returns a boolean (#420)

If it returns false it means that there was nothing to stop.

Sub-commits:
* Make audioPreview.stop() return bool.
* Add get current conference button to join screen

Author: graduad

ios/Classes/Bindings/AudioPreviewServiceBinding.swift

@@ -109,8 +109,7 @@ class AudioPreviewServiceBinding: Binding {
         flutterArguments: FlutterMethodCallArguments,
         completionHandler: FlutterMethodCallCompletionHandler
     ) {
-        audioPreview().stop()
-        completionHandler.success(flutterConvertible: true)
+       completionHandler.success(flutterConvertible: audioPreview().stop())
     }
 
     /// Release the internal memory and restart the audio session configuration.

lib/src/sdk_api/audio/audio_preview.dart

@@ -48,7 +48,7 @@ class AudioPreview {
   }
 
   /// Stops recording or playing an audio sample.
-  Future<void> stop() async {
+  Future<bool> stop() async {
     return await _methodChannel.invokeMethod("stop");
   }
 

test_app/lib/screens/join_screen.dart

@@ -385,6 +385,40 @@ class _JoinConferenceContentState extends State<JoinConferenceContent> {
                   color: Colors.deepPurple,
                 ),
                 const SizedBox(height: 16),
+                PrimaryButton(
+                  widgetText: const Text('Current conference'),
+                  onPressed: () async {
+                    try {
+                      var conference = await _dolbyioCommsSdkFlutterPlugin
+                          .conference
+                          .current();
+                      if (!mounted) return;
+
+                      if (conference == null) {
+                        ViewDialogs.dialog(
+                          context: context,
+                          title: "Conference",
+                          body: "Conference is null",
+                        );
+                      } else {
+                        ViewDialogs.dialog(
+                          context: context,
+                          title: "Conference",
+                          body: conference.toJson().toString(),
+                        );
+                      }
+                    } catch (error) {
+                      if (!mounted) return;
+                      ViewDialogs.dialog(
+                        context: context,
+                        title: "Error",
+                        body: error.toString(),
+                      );
+                    }
+                  },
+                  color: Colors.deepPurple,
+                ),
+                const SizedBox(height: 16),
                 PrimaryButton(
                   widgetText: const Text('Audio preview'),
                   onPressed: () {