JS: Add NumModules metric

javascript/ql/src/meta/analysis-quality/NumModules.ql

@@ -0,0 +1,14 @@
+/**
+ * @name Modules
+ * @description The number of modules in the snapshot.
+ * @kind metric
+ * @metricType project
+ * @metricAggregate sum
+ * @tags meta
+ * @id js/meta/modules
+ */
+
+import javascript
+import CallGraphQuality
+
+select projectRoot(), count(Module mod)