add testsuite (failing)

testsuite/rule-duplicate/main.tri

···
+rule single(1)
+rule single(2)
+rule single(3)
+
+rule double(a, a) <- single(a)
+
+proc main!() {
+  let mut n = 0
+  for double(a, b) {
+    assert a == b
+    n += a
+  }
+  assert n == 6
+}

testsuite/rule-with-body-simple/main.tri

···
-rule single(1)
-rule single(2)
-rule single(3)
+rule first(1)
 
-rule double(a, a) <- single(a)
+rule second(a) <- first(a)
 
 proc main!() {
   let mut n = 0
-  for double(a, b) {
-    assert a == b
+  for second(a) {
+    assert a == 1
     n += a
   }
-  assert n == 6
+  assert n == 1
 }