ExifOrientedBitmap was implemented before the introduction of the TIFF
decoder. So we had to provide a definition of the Orientation enum. Now
that we have a TIFF implementation that comes with some enum
definitions, we should prefer this source.
The idea behind this class is to provide an abstraction for decoders.
It allows them to use the class as if it was a normal `Bitmap`, however,
under the hood, this class will honor a given orientation, as specified
by the Exif standard. This class is introduced to be used within the
JPEG XL decoder, but it should be possible to use it for every
Exif-compatible format.
