[ROLES] Apply changes page and icon to be shown/hidden via dedicated permission

Actually it is possible for any user to see the "apply changes" icon in the top right of the GUI even if that user has no permission to apply changes.
Obviously, clicking the button opens a "you don't have permissions" page.

This forces an admin to give any user the "apply changes" permission to prevent the error page even if that user can't make any modification (ie. with a view-only role) or to rely to a "please don't mind the yellow icon" verbal warning.

Therefore the request is to create a specific permission that will enable or disable the "apply changes" page together with the icon in the top right of the GUI