Unified: Add test for Self access in nested class

Author: hvitved

unified/ql/test/library-tests/static-name-binding/explicit-instance-field-access.swift

@@ -45,3 +45,11 @@ private class B : A { // $ access=A
         return self.z // $ not handled by static name binding
     }
 }
+
+private class C {
+    static let x = 1
+    class D {
+        static let x = 2
+        static let foo = Self.x // $ access=C.D access=C.D.x $ SPURIOUS: access=C.x
+    }
+}