allow image posts from webhooks to be url links

Currently if you post an image in a webhook post using form-data, it's nice and clean looking, but clicking the image zooms to the image, there is no way to make the image an url link.  Allowing this would allow way cleaner and more professional webhook posts for cool integrations, right now they're kinda janky.  Also, if you do this, please don't just do it in embeds since I like the clean look of the plain attachments without the embed indent and quote bar.

Edit:  ugh, the attachments array works for setting the image description on mouseover but the url parm in the attachment doesn't make the image a link.

Related old request for this in text chat:  https://support.discord.com/hc/en-us/community/posts/360055784451-Insert-images-with-a-link-attached-to-it

Chris