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

js/js.translator/testData/box/delegation/delegationByExprWithArgs.kt

@@ -0,0 +1,18 @@
+package foo
+
+interface Base {
+    abstract fun foo(arg: String): String
+}
+
+class BaseImpl(val s1: String, val s2: String) : Base {
+    override fun foo(arg: String): String = "BaseImpl:foo ${s1}:${s2}:${arg}"
+}
+
+class Derived(s1: String, s2: String) : Base by BaseImpl(s1, s2)
+
+fun box(): String {
+    assertEquals("BaseImpl:foo arg1:arg2:!!", Derived("arg1", "arg2").foo("!!"), "delegation with two arguments")
+
+    return "OK"
+}
+