Kotlin: Add a file_classes consistency query

java/ql/consistency-queries/file_classes.ql

@@ -0,0 +1,9 @@
+import java
+
+// File classes should only be extracted if we need somewhere to
+// put top-level members.
+from Class c
+where file_class(c)
+  and not exists(c.getAMember())
+  and none() // TODO: This is currently broken
+select c