Improve feedback when dropping documents with Read permissions

Import document with Drag and drop (directly on the parent or by clicking on the create button)
Currently:

• Click on "Create" displays the message "ERROR: Forbidden"
• Click on "Add Properties" let the user fill all the properties and when click on create the message "ERROR: Privilege "Add Children" not granted to user"

User should see:

• when dropping items, a message explaining that he can't create anything in this container. An overlay with an icon (a pencil striked ) could also give a clue on the fact that the user can't create anything here.

When selecting a container in the creation / import pop up, a check is made to see if the user has the right to create on container listed (to check).