feat(core) Hide edit button when the user have no write rights

Also tweaked a bit multiPlugin so that it works in this case (useful for
 plugins configuration editing)
Changed reference tab to only return read rights so it does not get an
 edit button (makes no sense)
These changes means if you have only write rights on some configuration
 tab, you will have to go to that tab before clicking edit (the button
 won’t be there on other tabs)

issue #5858