[TD]Fix section snapping (fix #15961) (#15450)

* [TD]Add view snapping preferences

* [TD]fix section snapping algo

- snap sections to section normal line.
- snap views to other views in X&Y

* [TD]fix snapping to ProjectionGroups

src/Mod/TechDraw/App/DrawViewSection.h

@@ -134,7 +134,6 @@ public:
     virtual TopoDS_Shape getShapeToPrepare() const { return m_cutPieces; }
 
     //CS related methods
-    gp_Ax2 getProjectionCS(Base::Vector3d pt = Base::Vector3d(0.0, 0.0, 0.0)) const override;
     void setCSFromBase(const std::string sectionName);
     void setCSFromBase(Base::Vector3d localUnit);
     void setCSFromLocalUnit(const Base::Vector3d localUnit);
@@ -172,6 +171,8 @@ public:
 
     TopoDS_Shape makeFaceFromWires(std::vector<TopoDS_Wire> &inWires);
 
+    Base::Vector3d getCutCentroid() const;
+
 public Q_SLOTS:
     virtual void onSectionCutFinished(void);