feat(video_calls): added system android pip for calls

test/features/video_calls/presentation/video_call_session_cubit_test.dart

@@ -142,5 +142,32 @@ void main() {
 
       expect(cubit.state, const VideoCallSessionState());
     });
+
+    test('tracks whether call screen route is visible', () async {
+      when(
+        mockManager.startCall(
+          conversationUuid: anyNamed('conversationUuid'),
+          counterpartName: anyNamed('counterpartName'),
+          localParticipantName: anyNamed('localParticipantName'),
+          micEnabled: anyNamed('micEnabled'),
+          videoEnabled: anyNamed('videoEnabled'),
+        ),
+      ).thenAnswer((_) async {});
+
+      await cubit.onCallScreenVisible(conversationUuid: 'uuid');
+      expect(cubit.isCallScreenRouteVisible, isTrue);
+
+      cubit.emit(
+        const VideoCallSessionState(
+          conversationUuid: 'uuid',
+          connectPhase: VideoCallConnectPhase.connected,
+          callStageEntered: true,
+          uiMode: VideoCallUiMode.pip,
+        ),
+      );
+
+      cubit.onCallScreenDisposed();
+      expect(cubit.isCallScreenRouteVisible, isFalse);
+    });
   });
 }