Is your feature request related to a problem? Please elaborate.
Currently if a message is forwarded, the bot will show the message content. However, images are not shown. If a forward is only an image it will show “No content” like the image below.

Describe the solution you'd like
Forward images as well
Does your solution involve any of the following?
Describe alternatives you've considered
No alternative
Who will this benefit?
Staff using modmail in a situation where they could receive images.
Additional Information
No response