Move blackBoxFile() testData to box/ directory

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

compiler/testData/codegen/box/objects/kt1737.kt

@@ -0,0 +1,13 @@
+fun box(): String {
+    return object {
+        fun foo(): String {
+            val f = {}
+            object : Runnable {
+                public override fun run() {
+                    f()
+                }
+            }
+            return "OK"
+        }
+    }.foo()
+}