Reorganize tests and benchmark scripts.

Mainly to get rid of one top level directory. But this will
also be useful when there are tests of the embedding API.

test/language/list/newlines.wren

@@ -0,0 +1,10 @@
+// Allow after '[' and ',', and before ']'.
+var list = [
+
+"a",
+"b"
+
+]
+
+IO.print(list[0]) // expect: a
+IO.print(list[1]) // expect: b