[x] Move all icons in to MakerWorkbench/Resources/icons/
[x] Rename icons so that the workbench name precedes the name of the icon. This is future-friendly since FreeCAD documentation is striving to make all documentation uniform for better interoperability within itself and external workbenches. The convention is <Workbenchname>_<Command>.svg
MakerWorkbench/Resources/icons/<Workbenchname>_<Command>.svg