Add hook called when all client sessions for a user have been stopped#2066

rogersteblerbsi wants to merge 1 commit intoreleases/26.2eclipse-scout/scout.rt:releases/26.2from

features/rsb/26.2/423389_sessionsClosedeclipse-scout/scout.rt:features/rsb/26.2/423389_sessionsClosedCopy head branch name to clipboard