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

js/js.translator/testData/box/dataClass/components.kt

@@ -0,0 +1,16 @@
+package foo
+
+data class Dat(val start: String, val middle: String, val end: String) {
+    fun getLabel() : String {
+        return start + end
+    }
+}
+
+fun box(): String {
+    val d = Dat("max", "-", "min")
+    assertEquals("maxmin", d.getLabel())
+    val (p1, p, p2) = d
+    assertEquals("max", p1)
+    assertEquals("min", p2)
+    return "OK"
+}