Ensure that Toplevel::output() stays always in sync with geometry

Currently, if geometry updates are blocked, the Toplevel.output property
won't be updated. On the other hand, it's reasonable to use the output
property instead of manually looking up the output in window management
code, e.g. Workspace::clientArea().

In other words, using the Toplevel.output property is like walking on a
mine field, things can blow up. You can't use Toplevel.output even if it
makes perfect sense.

This change ensures that Toplevel.output property is always kept in sync
with the frame geometry. Unfortunately, this means that the output
property no longer can be updated when the frameGeometryChanged() signal
is emitted. It has to be done in moveResizeInternal() method.

BUG: 448064

(cherry picked from 510a41ee)

Part-of: <!2448>