Editor: Update layout accordingly when restoring state

Whenever blocks are folded/unfoled we need to request a layout update.

Task-number: QTCREATORBUG-6666
Change-Id: I123b99c697a034cb04871bc41f42eac4f39895a2
Reviewed-by: Daniel Teske <daniel.teske@nokia.com>
Reviewed-by: Eike Ziller <eike.ziller@nokia.com>
Reviewed-by: Leandro Melo <leandro.melo@nokia.com>