Cursors in GEF uses ImageDataProvider instead of ImageData

[arunjose696]

This change ensures that cursor images scale appropriately based on the display's zoom level .

Steps to reproduce

Steps to reproduce cursors are mentioned in vi-eclipse/Eclipse-Platform#331

To test with GEF, one should check out the GEF Classic repository: https://github.com/eclipse-gef/gef-classic Then import the org.eclipse.draw2d, org.eclipse.gef and the org.eclipse.gef.examples.logic (the latter for testing) to your Eclipse development workspace and add them to the product you are testing. With the "New" wizard, you can create a logic example to test out the cursors via inserting elements, dragging and dropping etc. (see also this issue for an example):
Cursors can be seen once a component is selected and mouse is moved around

Cursors from SharedCursors.java can be seen during selecting components in pallete and moving them to diagram.

Cursors from FlyoutPaletteComposite.java appear when dragging and repositioning the palette menu.

[ptziegler]

Outside of the minor refactoring, I'm happy with this one. Though perhaps it makes sense to wait for the SWT PR to be merged, just in case there are further adaptations needed.

[ptziegler]

The SWT PR has been merged, but I don't think it's included in the M1. However, this should be an issue as GEF will fail to find the expected constructor and fall back to the current implementation. @arunjose696 Thanks for PR and also for compromising on the backwards compatibility.