Move blackBoxFile() testData to box/ directory

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

compiler/testData/codegen/box/localClasses/noclosure.kt

@@ -0,0 +1,11 @@
+fun box(): String {
+    open class K {
+        val o = "O"
+    }
+
+    class Bar : K() {
+        val k = "K"
+    }
+
+    return K().o + Bar().k
+}