Move blackBoxFile() testData to box/ directory

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

compiler/testData/codegen/box/extensionFunctions/kt1290.kt

@@ -0,0 +1,14 @@
+//KT-1290 Method property in constructor causes NPE
+
+class Foo<T>(val filter: (T) -> Boolean) {
+    public fun bar(tee: T) : Boolean {
+        return filter(tee);
+    }
+}
+
+fun foo() = Foo({ (i: Int) -> i < 5 }).bar(2)
+
+fun box() : String {
+    if (!foo()) return "fail"
+    return "OK"
+}