Align pixel orientation with exif:Orientation in HEIC decoder (#1233)

Align pixel orientation with exif:Orientation in HEIC decoder (#1233)

* Align pixel orientation with exif:Orientation in HEIC decoder

It turns out that in HEIC the pixels are never rotated and the metadata only
indicates the orientation of the sensor when the photo was taken.

Hence, there was a discrepancy between `Image->orientation` and actual pixel
orientation in images loaded with the `heic` coder. Particularly, this led to
incorrect behavior of the `-auto-orient` which in this case tried to compensate
non-existing pixel rotation.

https://github.com/ImageMagick/ImageMagick/issues/1232