Add template specification for `SketcherAddWorkspaceSketchExtra`
for type `Gui::ToolBarItem` so that the following commands
are added to the toolbar as well as the Sketcher menu:
`ReorientSketch`, `ValidateSketch`, `MergeSketch`, `MirrorSketch`,
`StopOperation`.
Reorganize the order of the function declarations
so that they are in this order: Sketch actions (general),
geometries, constraints, tools, B-splines, and virtual space.
Add separators to the list of tools commands in the menu
so that it looks clearer.
Correct the header guard `#ifndef SKETCHER_WORKBENCH_H`.
Previously, it was using a guard `IMAGE_WORKBENCH_H`
seemingly copied from the Image Workbench.
b81ea41ae5