Sketcher: move GUI common utility functions to a new file Utils.h

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Common utility functions used by almost all Command classes were previous in Constraint.h.

Aside from providing a very bad intent, it created unnecessary header dependencies.

This commit separates these common functions into a new header, utils.h, which is then
used in all command classes where it is necessary.

src/Mod/Sketcher/Gui/EditDatumDialog.cpp

@@ -43,7 +43,7 @@
 #include "ViewProviderSketch.h"
 #include "ui_InsertDatum.h"
 #include "EditDatumDialog.h"
-#include "CommandConstraints.h"
+#include "Utils.h"
 
 
 using namespace SketcherGui;