Fixes issue with preview size and states
When state file is loaded pqMultiViewWidget is not visible and hence the choice it makes for widgets sizes is based on some default size than the actual size available on the screen. Fixed that by ensure preview-based wiget constraints are updated in resize-event. That also fixes #17855 (closed).
Fixes #19959 (closed).
Closes #19959 (closed), #17855 (closed)
Backport: release
Edited by Utkarsh Ayachit