Add a test case

Author: Linyxus

tests/neg-custom-args/captures/refine-withFile.scala

@@ -0,0 +1,8 @@
+import language.experimental.captureChecking
+
+trait File
+val useFile: [R] -> (path: String) -> (op: File^ -> R) -> R = ???
+def main(): Unit =
+  val f: [R] -> (path: String) -> (op: File^ -> R) -> R = useFile
+  val g: [R] -> (path: String) -> (op: File^{f*} -> R) -> R = f  // error
+  val leaked = g[File^{f*}]("test")(f => f)  // boom