add csharp query

Author: Jami Cogswell

csharp/ql/src/Telemetry/SupportedExternalApis.ql

@@ -0,0 +1,24 @@
+/**
+ * @name Usage of supported APIs coming from external libraries
+ * @description A list of supported 3rd party APIs used in the codebase. Excludes APIs exposed by test libraries.
+ * @kind metric
+ * @tags summary telemetry
+ * @id csharp/telemetry/supported-external-api
+ */
+
+private import csharp
+private import semmle.code.csharp.dispatch.Dispatch
+private import semmle.code.csharp.dataflow.internal.FlowSummaryImpl as FlowSummaryImpl
+private import ExternalApi
+
+private predicate relevant(ExternalApi api) {
+  not api.isUninteresting() and
+  (
+    api.isSupported() or
+    api instanceof FlowSummaryImpl::Public::NegativeSummarizedCallable
+  )
+}
+
+from string info, int usages
+where Results<relevant/1>::restrict(info, usages)
+select info, usages order by usages desc