switchCamera method
Changes the state of the camera (front or back).
Does nothing if the device has no front camera.
Implementation
Future<void> switchCamera() async {
await _methodChannel.invokeMethod('stop');
final CameraFacing facingToUse =
cameraFacingState.value == CameraFacing.back
? CameraFacing.front
: CameraFacing.back;
await start(cameraFacingOverride: facingToUse);
}