Image attachment corruption

[georgweiss]

Discovered in a log entry: an image transferred from iPhone in HEIC format was converted to jpeg in the Mac OS Preview app. That conversion apparently is very Mac OS centric. See hex dumps in attached files.

The converted file can be opened in the Preview app, but not in a browser. In the Phoebus Olog client a call like
ImageIO.read(attachment.getFile());
will in this case return null and not throw an exception.

Will address this in the log editor such that the UI will indicate the null case (e.g. "Cannot load image"), but it is still up to the user to inspect image files in the attachments preview.

Corrupt jpeg:

Non-currupt (different image data):