Allow sending images in direct messages

[Eddippla]

I use the direct message feature a lot in my own forum, however I feel that it is lacking a pretty normal feature, uploading images in direct messages. I believe that they would be used much more and would serve more of a purpose, as currently you can only send text.

[baris]

This will be available in 1.19.2, will also allow drag drop in the quick reply box in persona
https://github.com/NodeBB/NodeBB/issues/6388