feat: restart to apply update, privileged helper, rollback

api/pkg/apperr/messages.go

@@ -33,3 +33,4 @@ const UpdateNotPreparedErrorMessage = "This server cannot update itself yet."
 const UpdateAlreadyRunningErrorMessage = "An update is already running or waiting to be installed."
 const NothingToUpdateErrorMessage = "There is nothing to update."
 const UpdateRefusedErrorMessage = "This update cannot be downloaded."
+const UpdateRestartMismatchErrorMessage = "The update state changed. Reload the page and try again."