feat: Add rotation to ios

[juanmartin8a]

Add the rotation functionality to iOS. It rotates the image with the given rotation parameter from the InputImage metadata. I use it to rotate the image when the camera in flutter is locked to "portrait up".

[fbernaly]

I think this should be added to this file instead: https://github.com/flutter-ml/google_ml_kit_flutter/blob/master/packages/google_mlkit_commons/ios/Classes/MLKVisionImage%2BFlutterPlugin.m#L6-L18

[juanmartin8a]

I think this should be added to this file instead: https://github.com/flutter-ml/google_ml_kit_flutter/blob/master/packages/google_mlkit_commons/ios/Classes/MLKVisionImage%2BFlutterPlugin.m#L6-L18

Done :)

[fbernaly]

This changes are breaking the example app. I will need to revert them. Please submit another PR and make sure our example app works correctly with all the APIs.

Look at this code to include all the possible rotations and camera lens options. Your switch case does not include all of them: https://developers.google.com/ml-kit/vision/face-detection/ios#2.-prepare-the-input-image

It should be something like this:

- (UIImageOrientation)
  imageOrientationFromDeviceOrientation:(UIDeviceOrientation)deviceOrientation
                         cameraPosition:(AVCaptureDevicePosition)cameraPosition {
  switch (deviceOrientation) {
    case UIDeviceOrientationPortrait:
      return cameraPosition == AVCaptureDevicePositionFront ? UIImageOrientationLeftMirrored
                                                            : UIImageOrientationRight;

    case UIDeviceOrientationLandscapeLeft:
      return cameraPosition == AVCaptureDevicePositionFront ? UIImageOrientationDownMirrored
                                                            : UIImageOrientationUp;
    case UIDeviceOrientationPortraitUpsideDown:
      return cameraPosition == AVCaptureDevicePositionFront ? UIImageOrientationRightMirrored
                                                            : UIImageOrientationLeft;
    case UIDeviceOrientationLandscapeRight:
      return cameraPosition == AVCaptureDevicePositionFront ? UIImageOrientationUpMirrored
                                                            : UIImageOrientationDown;
    case UIDeviceOrientationUnknown:
    case UIDeviceOrientationFaceUp:
    case UIDeviceOrientationFaceDown:
      return UIImageOrientationUp;
  }
}

[juanmartin8a]

Sure. Should the rotation be determined using the device orientation directly on obj-c or using the rotation parameter that is sent in the metadata through the channel?