add get_total_used_size (#913)

Author: larshp

src/memory/cl_abap_memory_utilities.clas.abap

@@ -20,10 +20,17 @@ CLASS cl_abap_memory_utilities DEFINITION PUBLIC.
       EXPORTING
         size TYPE abap_msize.
 
+    CLASS-METHODS get_total_used_size
+      EXPORTING
+        size TYPE abap_msize.
+
     CLASS-METHODS do_garbage_collection.
 ENDCLASS.
 
 CLASS cl_abap_memory_utilities IMPLEMENTATION.
+  METHOD get_total_used_size.
+    RETURN. " todo, implement method
+  ENDMETHOD.
 
   METHOD do_garbage_collection.
     RETURN. " todo, implement method