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

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

@@ -0,0 +1,26 @@
+// This test was adapted from compiler/testData/codegen/box/callableReference/function/.
+package foo
+
+fun run(arg1: A, arg2: String, funRef:A.(String) -> Unit): Unit {
+    return arg1.funRef(arg2)
+}
+
+class A {
+    var result = "Fail"
+}
+
+fun A.foo(newResult: String) {
+    result = newResult
+}
+
+fun box(): String {
+    val a = A()
+    val x = A::foo
+    x(a, "OK")
+
+    if (a.result != "OK") return a.result
+
+    val a1 = A()
+    run(a1, "OK", A::foo)
+    return a.result
+}