Add filter for extremely large files

[Webreaper]

Huge images (greater than 400MB) cause the AI and other processes to fail. Default to skipping them, but provide an option to allow them.

Depending on what is causing the crash this might be good to investigate. E.g, if it's just ImageSharp or similar crashing when resizing the image for AI processing, it may be possible to work around it by doing it using Skia or ImageMagick.

Fixes #463.