Kotlin: Add test case for confusingly overloaded $default method

Author: tamasvajk

java/ql/test/kotlin/query-tests/ConfusingMethodSignature/ConfusingMethodSignature.expected

@@ -0,0 +1 @@
+| Test.kt:12:5:12:45 | fn$default | Method A.fn$default(..) could be confused with overloaded method $@, since dispatch depends on static types. | Test.kt:13:5:13:40 | fn$default | fn$default |

java/ql/test/kotlin/query-tests/ConfusingMethodSignature/Test.kt

@@ -7,3 +7,8 @@ class C {
         prop(this)
     }
 }
+
+class A {
+    fun <T : Any> fn(value: T, i: Int = 1) {}
+    fun fn(value: String, i: Int = 1) {}
+}