Move blackBoxFile() testData to box/ directory

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

compiler/testData/codegen/box/properties/kt1714.kt

@@ -0,0 +1,23 @@
+trait A {
+    val method : (() -> Unit )?
+    val test : Integer
+}
+
+class AImpl : A {
+    override val method : (() -> Unit )? = {
+    }
+    override val test : Integer = Integer(777)
+}
+
+fun test(a : A) {
+    val method = a.method
+    if (method != null) {
+        method()
+    }
+}
+
+public fun box() : String {
+    AImpl().test
+    test(AImpl())
+    return "OK"
+}