Change joystick settings icon to game controller

Summary:
Most of the "joysticks" that people have are game controllers, so a complete controller is better than just a D-pad.

BUG: 406679
FIXED-IN: 5.60

Test Plan:
left: old, right: new
{F6917203, size=full}

Reviewers: #vdg, ngraham

Reviewed By: #vdg, ngraham

Subscribers: usta, davidedmundson, kde-frameworks-devel

Tags: #frameworks

Differential Revision: https://phabricator.kde.org/D21919