update discord images

[walkingeyerobot]

if a user updates their image, their old image will 404. If this happens, the client should tell the server that it 404'd, the server should then verify that it does and then request a new url from discord, and then inform the client of the new url. Limit this to one request at a time per user image.

What we don't want is the server constantly asking discord for new images, and we don't want to give the client the ability to have the server repeatedly asking discord for new images.

I don't actually know the correct way to do this. I'm guessing.

I'm giving this the server label only. Once the server work is done, we can hand it to the client for changes on that side.