Support opening a fork directly from a github link

[Janpot]

🌈 Feature

Stackblitz offers the ability to craft links that immediately fork the sandbox: https://developer.stackblitz.com/guides/integration/open-from-github#open-directly-or-fork

This is useful to us as our sandboxes modify their own repository directory. We don't want every visitor to operate on the same sandbox and interfere with each other.

[djsnipa1]

If you edit the url of a GitHub repo from github.com/user/repo to githubbox.com/user/repo it will do what you are asking. So just add the word box before the .com