Do not detect Ultra HDR images as MPO

[radarhere]

Resolves #8052

The Ultra HDR format stores its gain map as an additional MPO image. However, as the issue has found, because we do not support Ultra HDR images, the additional image appears incorrectly.

Instead, this PR treats such files as standard JPEGs.

https://developer.android.com/media/platform/hdr-image-format#signal_of_the_format details how this format can be detected.

A JPEG file conforming to this format may be identified by the presence of hdrgm:Version="1.0" in the primary image's XMP packet