PartDesign: change feature DressUp behavior when used for pattern

Repurpose DressUp.SupportTransform property to define the following
behavior,

* When disabled (default), only the dressing will be used for patterning.

* When enabled, the additive/subtractive shape of the dressed base
  feature will be used for patterning. Any dressing that is not applied
  to the based feature will be ignored.

* If the dressing is applied to non-additive/subtractive feature, then
  only the dressing will be used for patterning.

New API FreatureAddSub::getAddSubShape() is added to account for the
fact that a dressing (e.g. a fillet) can be either additive or
subtractive, which means that a DressUP feature may contain both
additive and subtractive shapes.

FeatureTransformed is modified to perform both fusion and cut if
required.

src/Mod/PartDesign/App/FeatureAddSub.cpp

@@ -81,6 +81,14 @@ TopoDS_Shape FeatureAddSub::refineShapeIfActive(const TopoDS_Shape& oldShape) co
     return oldShape;
 }
 
+void FeatureAddSub::getAddSubShape(Part::TopoShape &addShape, Part::TopoShape &subShape)
+{
+    if (addSubType == Additive)
+        addShape = AddSubShape.getShape();
+    else if (addSubType == Subtractive)
+        subShape = AddSubShape.getShape();
+}
+
 }
 
 namespace App {