Add a TupleXXL unreachable test case

Author: dwijnand

tests/warn/i19084.scala

@@ -0,0 +1,17 @@
+
+
+class Test:
+  def t1(y: (
+    Int, Int, Int, Int, Int, Int, Int, Int, Int, Int,
+    "Bob", Int, 33, Int,
+    Int, Int, Int, Int, Int, Int, Int, Int, Int, Int)
+        ): Unit = y match
+    case b @ (x0, x1, x2, x3, x4, x5, x6, x7, x8, x9,
+          "Bob", y1, 33, y2,
+          z0, z1, z2, z3, z4, z5, z6, z7, z8, z9)
+     => ()
+    case b @ (x0, x1, x2, x3, x4, x5, x6, x7, x8, x9, // warn: unreachable
+          "Bob", y1, 33, y2,
+          z0, z1, z2, z3, z4, z5, z6, z7, z8, z9)
+     => ()
+    case _ => ()