fix: updating logic for REPLACE loadtype

Staged rows are always considered as NEW, and previous rows are considered DELETED
This is consistent with the fact that REPLACE involves a delete *, followed by an append.

sas/sasjs/macros/mpe_targetloader.sas

@@ -142,10 +142,14 @@ run;
     %mp_lockanytable(UNLOCK,lib=&lib,ds=&ds,ctl_ds=&dclib..mpe_lockanytable)
   %end;
   %else %do;
-    /* is full replace so treat everything as a mod in diff screen */
-    data work.outds_mod work.outds_add work.outds_del;
+    /* is full replace so treat all staged records as new in diff screen */
+    data work.outds_mod work.outds_add ;
       set work.&staging_ds;
-      output work.outds_mod; /* _add and _del will be empty */
+      output work.outds_add;
+    run;
+    /* previous table will be considered fully deleted */
+    data work.outds_del;
+      set &lib..&ds;
     run;
   %end;
 %end;