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/003/aiken.toml

@@ -0,0 +1,2 @@
+name = "acceptance_test_003"
+version = "0.0.0"

examples/acceptance_tests/003/lib/test.ak

@@ -0,0 +1,14 @@
+pub fn foldr(xs: List<a>, f: fn(a, b) -> b, zero: b) -> b {
+  when xs is {
+    [] -> zero
+    [x, ..rest] -> f(x, foldr(rest, f, zero))
+  }
+}
+
+pub fn concat(left: List<a>, right: List<a>) -> List<a> {
+  foldr(left, fn(x, xs) { [x, ..xs] }, right)
+}
+
+test concat_1() {
+  concat([1, 2, 3], [4, 5, 6]) == [1, 2, 3, 4, 5, 6]
+}