Move blackBoxFile() testData to box/ directory

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

compiler/testData/codegen/box/classes/kt2482.kt

@@ -0,0 +1,9 @@
+public fun box() : String {
+    if ( 0 == 0 ) { // Does not crash if either this...
+        if ( 0 == 0 ) { // ...or this is changed to if ( true )
+            // Does not crash if the following is uncommented.
+            //println("foo")
+        }
+    }
+    return "OK"
+}