Restore sidebar to previous state after terminating a debug session

[fpbfpb]

Following issue #1931 "Sidebar remains in debug section after terminating a debug session" a debug.openExplorerOnEnd option has been added to reopen explorer after a debug session terminates. I think restoring the state of the sidebar preceding the debug session would be a better option.

If the sidebar is hidden to maximize editor area during development mode, most of time we want to terminate a debug session with the sidebar hidden. If we want to keep it visible and go to a specific item (debug, explorer, ...) just open that item before starting the debug session so the sidebar will be restored to that state after the debug session terminates.

debug.restoreSidebarOnEnd