For a public repo, even an anonymous user can read everything in it, but only the owner and collaborators are allowed to edit. In this PR: we further distinguish the access for different roles in a repo, enforced the access rule both on the front-end and back-end side.

• front-end: hide operation UI for guests, including auto saving button, runtime kernel in the sidebar, new code/scope menu
• back-end: prohibit mutate query when auth fails

Besides, remove the awareness info (remote cursor/selection) of guests, only show the operation update from an owner/collaborator. A guest can never edit/run code in the pod or drag a pod.

Now, a public repo can also be shared with collaborators.

TODO

• the resizing button and drag handles sometimes do not work properly when multiple users are collaborating on the repo.