C#: Re-factor SettingsDataFlow to use the new API.

Author: michaelnebel

csharp/ql/lib/semmle/code/csharp/frameworks/system/Xml.qll

@@ -162,18 +162,14 @@ class XmlReaderSettingsCreation extends ObjectCreation {
   }
 }
 
-private class SettingsDataFlowConfig extends DataFlow3::Configuration {
-  SettingsDataFlowConfig() { this = "SettingsDataFlowConfig" }
+private module SettingsDataFlowConfig implements DataFlow::ConfigSig {
+  predicate isSource(DataFlow::Node source) { source.asExpr() instanceof XmlReaderSettingsCreation }
 
-  override predicate isSource(DataFlow::Node source) {
-    source.asExpr() instanceof XmlReaderSettingsCreation
-  }
-
-  override predicate isSink(DataFlow::Node sink) {
-    sink.asExpr() instanceof XmlReaderSettingsInstance
-  }
+  predicate isSink(DataFlow::Node sink) { sink.asExpr() instanceof XmlReaderSettingsInstance }
 }
 
+private module SettingsDataFlow = DataFlow::Global<SettingsDataFlowConfig>;
+
 /** A call to `XmlReader.Create`. */
 class XmlReaderCreateCall extends MethodCall {
   XmlReaderCreateCall() { this.getTarget() = any(SystemXmlXmlReaderClass r).getCreateMethod() }
@@ -190,8 +186,6 @@ class XmlReaderSettingsInstance extends Expr {
 
   /** Gets a possible creation point for this instance of `XmlReaderSettings`. */
   XmlReaderSettingsCreation getASettingsCreation() {
-    exists(SettingsDataFlowConfig settingsFlow |
-      settingsFlow.hasFlow(DataFlow::exprNode(result), DataFlow::exprNode(this))
-    )
+    SettingsDataFlow::flow(DataFlow::exprNode(result), DataFlow::exprNode(this))
   }
 }