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/kt694.kt

@@ -0,0 +1,18 @@
+enum class Test {
+    A
+    B
+    C
+}
+
+fun checkA(a: Test) = when(a) {
+    Test.B -> false
+    Test.A -> true
+    else -> false
+}
+
+fun box() : String {
+    if(!checkA(Test.A)) return "fail"
+    if( checkA(Test.C)) return "fail"
+    if( checkA(Test.B)) return "fail"
+    return "OK"
+}