Move blackBoxFile() testData to box/ directory

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

compiler/testData/codegen/box/enum/kt1119.kt

@@ -0,0 +1,12 @@
+enum class Direction() {
+    NORTH {
+        val someSpecialValue = "OK"
+
+        override fun f() = someSpecialValue
+    }
+
+
+    abstract fun f():String
+}
+
+fun box() = Direction.NORTH.f()