JS: create new common directory for all generated tests, migrate several tests there

js/js.translator/testData/box/closure/deepInnerClassInLocalClassFromExtension.kt

@@ -0,0 +1,23 @@
+package foo
+
+class A() {
+    fun test(): Int {
+        open class B(open val x: Int) {
+            inner class C(x: Int) : B(x * 10) {
+                inner class D() {
+                    fun baz() = bar()
+                }
+
+                fun D.bar() = { x + this@B.x }
+            }
+        }
+
+
+        return B(3).C(2).D().baz()()
+    }
+}
+
+fun box(): String {
+    assertEquals(23, A().test())
+    return "OK"
+}