QuickAccessEntry uses an image data provider returning the same image
data at every zoom. That's breaks the assumption of an image to have a
linear scaling of the image's / image data's bounds according to the
zoom, potentially leading to errors when drawing scaled version.

This change corrects the image data provider in
OpenResourceQuickAccessComputer used by QuickAccessEntry to return image
data at the proper zoom.

Fixes https://github.com/eclipse-platform/eclipse.platform.ui/issues/3006