JS: Add tests for functions with "use server" directive

Author: asgerf

javascript/ql/test/library-tests/frameworks/ReactJS/use-server1.js

@@ -0,0 +1,10 @@
+async function getData(
+    x, // $ MISSING: threatModelSource=remote
+    y) { // $ MISSING: threatModelSource=remote
+  "use server";
+}
+
+async function getData2(
+    x, // should not be remote flow sources (because the function does not have "use server")
+    y) {
+}

javascript/ql/test/library-tests/frameworks/ReactJS/use-server2.js

@@ -0,0 +1,11 @@
+"use server";
+
+export async function getData(
+    x, // $ MISSING: threatModelSource=remote
+    y) { // $ MISSING: threatModelSource=remote
+}
+
+async function getData2(
+    x, // should not be remote flow sources (because the function is not exported)
+    y) {
+}