URL argument type for slash commands

[xSke]

Description

An attachment type, similar to string, that performs client-side validation that the input is a valid URL.

Why This is Needed

I have a lot of commands in my bot that can take eg. links to images to use, links to files elsewhere, etc... and it's nice to have some sort of first-class indication that an argument needs to be an URL.

Alternatives Considered

The alternative would be just using a string argument, and performing the validation on the bot end. That works, but it's not as clean for the user.

Additional Details
This isn't super important, but it'd be a nice quality-of-life addition, depending on how difficult new argument types are to add on your end.

[k9lego]

Better yet, some kind of Regular Expression or "fake" Regular Expression (to prevent users from killing Discord's servers) would be nice