rename examples/tests/{a,b,c,d,e,f} into examples/acceptance_tests/00{1,2,3,4,5,6}

Also added a little Makefile to run them all in one go.

examples/acceptance_tests/002/aiken.toml

@@ -0,0 +1,2 @@
+name = "acceptance_test_002"
+version = "0.0.0"

examples/acceptance_tests/002/lib/test.ak

@@ -0,0 +1,11 @@
+pub fn repeat(x: a, n: Int) -> List<a> {
+  if n <= 0 {
+    []
+  } else {
+    [x, ..repeat(x, n - 1)]
+  }
+}
+
+test repeat_1() {
+  repeat("aiken", 2) == ["aiken", "aiken"]
+}