[TD]Symbol scaling (fix #14400) (#18757)

* [TD]add legacy/new svg scaling pref

* [TD]Change Svg scaling logic (fix 14400)

src/Mod/TechDraw/App/Preferences.h

@@ -157,6 +157,8 @@ public:
     static bool checkShapesBeforeUse();
     static bool debugBadShape();
 
+    static bool useLegacySvgScaling();
+
 };