Move blackBoxFile() testData to box/ directory

Delete all test methods (and empty test classes), since they'll be
auto-generated

compiler/testData/codegen/box/bridges/simpleEnum.kt

@@ -0,0 +1,20 @@
+trait A<T> {
+    open fun foo(t: T) = "A"
+}
+
+enum class Z(val name: String) : A<String> {
+    Z1 : Z("Z1")
+    Z2 : Z("Z2")
+    override fun foo(t: String) = name
+}
+
+
+fun box(): String {
+    return when {
+        Z.Z1.foo("")               != "Z1" -> "Fail #1"
+        Z.Z2.foo("")               != "Z2" -> "Fail #2"
+        (Z.Z1 : A<String>).foo("") != "Z1" -> "Fail #3"
+        (Z.Z2 : A<String>).foo("") != "Z2" -> "Fail #4"
+        else -> "OK"
+    }
+}