Frontend: permission levels for campaigns

Created by: mrnugget

Taken from RFC 157.

Depends on https://github.com/sourcegraph/sourcegraph/issues/10808

Tasks

• Depending on campaign.viewerCanAdminister, hide/disable following buttons:
  • Edit
  • Close
  • Delete
  • Publish (maybe: don't show the "publish"-box at all)
  • Retry
  • Don't show the complete "add changesets" form
  • Publish button next to patches
  • "Sync now" button
• Adjust error message when changeset publication failed, since no errors are returned
• Show message on "preview update" view: "You don't have permission to update this campaign"