Dataflow: Add support for C#/Python/Ruby/Swift.

csharp/ql/lib/semmle/code/csharp/dataflow/internal/DataFlowPrivate.qll

@@ -1581,6 +1581,8 @@ predicate jumpStep(Node pred, Node succ) {
     jrk.getTarget() = call.getATarget(_) and
     succ = getAnOutNode(call, jrk.getTargetReturnKind())
   )
+  or
+  FlowSummaryImpl::Private::Steps::summaryJumpStep(pred, succ)
 }
 
 private class StoreStepConfiguration extends ControlFlowReachabilityConfiguration {

csharp/ql/lib/semmle/code/csharp/dataflow/internal/FlowSummaryImplSpecific.qll

@@ -91,6 +91,12 @@ DataFlowType getCallbackReturnType(DataFlowType t, ReturnKind rk) {
   )
 }
 
+/** Gets the type of synthetic global `sg`. */
+DataFlowType getSyntheticGlobalType(SummaryComponent::SyntheticGlobal sg) {
+  exists(sg) and
+  result = Gvn::getGlobalValueNumber(any(ObjectType t))
+}
+
 bindingset[provenance]
 private boolean isGenerated(string provenance) {
   provenance = "generated" and result = true