Restore nullability annotations

This is imperfect since arguments to those annotations will be missing, but at least the common case of a plain `@NotNull` or `@Nullable` will be right, and the `@NotNull`s introduced by the Kotlin compiler will be present as expected.

java/ql/integration-tests/all-platforms/kotlin/nullability-annotations/JavaUser.java

@@ -0,0 +1,7 @@
+public class JavaUser {
+
+  public static void test(KotlinAnnotatedMethods km) {
+    km.f(null);
+  }
+
+}