deprecate the unused localTaintStep and stringStep predicates

Author: erik-krogh

javascript/ql/lib/semmle/javascript/dataflow/DataFlow.qll

@@ -1718,5 +1718,5 @@ module DataFlow {
   import TypeTracking
   import internal.FunctionWrapperSteps
 
-  predicate localTaintStep = TaintTracking::localTaintStep/2;
+  deprecated predicate localTaintStep = TaintTracking::localTaintStep/2;
 }

javascript/ql/lib/semmle/javascript/dataflow/TaintTracking.qll

@@ -431,7 +431,7 @@ module TaintTracking {
    * Holds if `pred -> succ` is a taint propagating data flow edge through a string operation.
    */
   pragma[inline]
-  predicate stringStep(DataFlow::Node pred, DataFlow::Node succ) {
+  deprecated predicate stringStep(DataFlow::Node pred, DataFlow::Node succ) {
     stringConcatenationStep(pred, succ) or
     stringManipulationStep(pred, succ)
   }
@@ -1243,7 +1243,7 @@ module TaintTracking {
   /**
    * Holds if taint propagates from `pred` to `succ` in one local (intra-procedural) step.
    */
-  predicate localTaintStep(DataFlow::Node pred, DataFlow::Node succ) {
+  deprecated predicate localTaintStep(DataFlow::Node pred, DataFlow::Node succ) {
     DataFlow::localFlowStep(pred, succ) or
     sharedTaintStep(pred, succ)
   }