馃崚 shell: emit screenGeometryChanged when panel is ready
When screenGeometryChanged is emitted in handleScreenOrderChanged
,
only desktops are ready. Panels are still in the waiting list and do not
have a associated containment, so those containments do not have a valid
id for screen, which is required to get a valid screen geometry.
BUG: 482339 BUG: 481736 FIXED-IN: 6.0.3
(cherry picked from commit 6d543aca)