Move blackBoxFile() testData to box/ directory

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

compiler/testData/codegen/box/functions/invoke.kt

@@ -0,0 +1,28 @@
+package invoke
+
+fun test1(predicate: (Int) -> Int, i: Int) = predicate(i)
+
+fun test2(predicate: (Int) -> Int, i: Int) = predicate.invoke(i)
+
+class Method {
+    fun invoke(i: Int) = i
+}
+
+fun test3(method: Method, i: Int) = method.invoke(i)
+
+fun test4(method: Method, i: Int) = method(i)
+
+class Method2 {}
+
+fun Method2.invoke(s: String) = s
+
+fun test5(method2: Method2, s: String) = method2(s)
+
+fun box() : String {
+    if (test1({ it }, 1) != 1) return "fail 1"
+    if (test2({ it }, 2) != 2) return "fail 2"
+    if (test3(Method(), 3) != 3) return "fail 3"
+    if (test4(Method(), 4) != 4) return "fail 4"
+    if (test5(Method2(), "s") != "s") return "fail5"
+    return "OK"
+}