Windows QPA: Scale hotspot of custom cursors correctly.

Separate factors in QWindowsCursor::createPixmapCursor()
and apply factor to the hotspot.

Task-number: QTBUG-52276
Change-Id: Ia5a5db39ddc2bc4215a23ff8625431af9b4a76d8
Reviewed-by: Adam Light <aclight@gmail.com>
Reviewed-by: Oliver Wolff <oliver.wolff@theqtcompany.com>