JS: Add test for dynamic imports

Author: asgerf

javascript/ql/test/library-tests/UnderlyingTypes/dynamicImportLib.ts

@@ -0,0 +1,4 @@
+import * as express from 'express';
+
+export async function getRequest(): express.Request {
+}

javascript/ql/test/library-tests/UnderlyingTypes/dynamicImportUse.ts

@@ -0,0 +1,4 @@
+async function t1() {
+    const e = await import('./dynamicImportLib');
+    e.getRequest(); // $ MISSING: hasUnderlyingType='express'.Request
+}