This enables showing preview tooltip for 2D (Item based) components.
We render the component from scratch for this purpose instead of using
existing renders done for form editor to ensure preview doesn't
include any local changes to component.
Also cache tooltips as QPixmaps in NodeInstanceView instead of QImages
to avoid unnecessary image to pixmap conversions when using cached
data.
Change-Id: I3082c5c846f605a765a81408767266d1ff7a12d7
Fixes: QDS-2762
Reviewed-by: Thomas Hartmann <thomas.hartmann@qt.io>
Reviewed-by: Mahmoud Badri <mahmoud.badri@qt.io>