Fix uncentered crosshairs
Summary: For some reason, the centers of the generated PNGs are not the centers of the crosshairs. I had to move the 1x crosshairs down and to the left by 2px, the 1.5x crosshairs by 3px and the 2x crosshairs by 3px (it's more centered than 4px).
Test Plan:
Breeze 1x
Breeze 1.5x
Breeze 2x
Breeze Snow 1x
Breeze Snow 1.5x
Breeze Snow 2x
Reviewers: VDG, Breeze, Plasma, ngraham
Reviewed By: VDG, Breeze, ngraham
Subscribers: ngraham, plasma-devel, Plasma, Breeze, VDG
Tags: Plasma
Differential Revision: https://phabricator.kde.org/D17038