0024830: Remove redundant keyword 'mutable' in CDL declarations

Redundant keyword 'mutable' removed in CDL files.
In IGESConvGeom_GeomBuilder, unused methods MakeXY() and MakeXYZ() removed.
Method StepAP214_AutoDesignGroupAssignment::Init() replicating same method of the base class is removed as it causes CDL extraction error after above (seemingly irrelevant) changes.

src/STEPCAFControl/STEPCAFControl_Controller.cdl

@@ -25,7 +25,7 @@ uses
 
 is
 
-    Create returns mutable Controller;
+    Create returns Controller;
     ---Purpose : Initializes the use of STEP Norm (the first time)
 
     Init (myclass) returns Boolean;