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.