feat: downloads url uploads on the server to allow for external url uploads

[PatrikKozak]

What?

Previously, the url uploads option only allowed using links from a users payload domain - which meant not being able to download images from a users browser without running into CORS errors

How?

Now, we download the image on the server first, and then stream it to the browser.

We do this by:

• opening a new payload endpoint called paste-url i.e /api/paste-url
• this endpoint then accepts a query param for the image - i.e. /api/paste-url?src=https://google.com/image.png
• the endpoint streams the src image back
• then, the paste URL function in the upload collection simply gets the image from that new Payload URL rather than directly, which would prevent CORS

TODO:

• Add tests