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

js/js.translator/testData/box/callableReference/function/extensionWithClosure.kt

@@ -0,0 +1,14 @@
+// This test was adapted from compiler/testData/codegen/box/callableReference/function/local/.
+package foo
+
+class A
+
+fun box(): String {
+    var result = "Fail"
+
+    fun A.ext() { result = "OK" }
+
+    val f = A::ext
+    f(A())
+    return result
+}