C#: Add isAutoGenerated predicate to SummarizedCallable.

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

@@ -219,6 +219,11 @@ module Public {
      */
     pragma[nomagic]
     predicate clearsContent(ParameterPosition pos, ContentSet content) { none() }
+
+    /**
+     * Gets whether the summary is auto generated or not.
+     */
+    boolean isAutoGenerated() { result = false }
   }
 }
 
@@ -898,6 +903,8 @@ module Private {
           kind = "taint" and preservesValue = false
         )
       }
+
+      override boolean isAutoGenerated() { summaryElement(this, _, _, _, result) }
     }
 
     /** Holds if component `c` of specification `spec` cannot be parsed. */