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/kt1165.kt

@@ -0,0 +1,13 @@
+public abstract class VirtualFile() {
+    public abstract val size : Long
+}
+
+public class PhysicalVirtualFile : VirtualFile() {
+    public override val size: Long
+    get() = 11
+}
+
+fun box() : String {
+    PhysicalVirtualFile()
+    return "OK"
+}