CORS issue caused by URL change

[oxguy3]

This tool used to be hosted at https://tools.wmflabs.org/convert/, but has been moved to https://convert.wmflabs.org/ with a 308 redirect. This was a breaking change for any user scripts or other client-side code that uses this tool, as this causes the Origin header to be set to null, which causes this tool to respond with a 403 Forbidden error.

I've started a discussion to update the URL in SVGedit.js here: https://commons.wikimedia.org/wiki/User_talk:Rillke/SVGedit.js#Previews_broken_by_server_redirect. I'm creating this issue because I don't know what other user scripts might exist that are also broken by this change.