Emulation of non-logical coordinate mode gradients was implemented by
essentially 3 x 2 repetitions of the same manipulation of the QBrush
transform. Avoid the code duplication by extracting a common method.
Add lancelot test scripts that excersizes these code paths.
Change-Id: I7baa921923231ef9e83e443dba996b82b32ad1e7
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>
