is not enough. This needs to be done recursively, ie notify the
listeners, notify the listeners of the listeners and so on.
ScDocument::BroadcastCells() seems to do exactly that, so lets
use it here intead of collect+notify.

Change-Id: Ifa273fea5f08af661958cd9b4c3d01d9044b8727
Reviewed-on: https://gerrit.libreoffice.org/70044Reviewed-by: Dennis Francis <dennis.francis@collabora.com>
Tested-by: Dennis Francis <dennis.francis@collabora.com>