Improve logout user experience

[temi]

Existing behaviour
At the moment, if a user logs out of a private collection, it will take them to the not authorised page. This can be confusing as the message says "You do not have the necessary permissions to perform this action."

Expected behaviour
Take users to a page saying you are successfully logged out. Also, make sure if user logged out from public collection they are taken to the public page they logged out from. If the current page require user to be logged in, then take them to collection home page.