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

js/js.translator/testData/box/callableReference/property/topLevelVar.kt

@@ -0,0 +1,20 @@
+package foo
+
+var x = 1
+
+val y = 2
+
+fun box(): String {
+    var refX = ::x
+    assertEquals(1, refX.get())
+    assertEquals("x", refX.name)
+
+    refX.set(100)
+    assertEquals(100, x)
+
+    var refY = ::y
+    assertEquals(2, refY.get())
+    assertEquals("y", refY.name)
+
+    return "OK"
+}