Change the contract of the formatters

Both `ArrayFormatter` and `StringFormatter` accept an instance of the
`Translator`. Thinking about it a bit better, I realised that a
formatter might not always need a `Translator`, but it will surely need
a `Renderer`.

Besides, the `InterpolationRenderer` needs to take translation into
account, so it seems more natural to me that this is the one that will
get an instance of the `Translator`, as other implementations of the
`Renderer` might not even deal with translations.

library/Message/ArrayFormatter.php

@@ -18,5 +18,5 @@ interface ArrayFormatter
      *
      * @return array<string, mixed>
      */
-    public function format(Result $result, array $templates, Translator $translator): array;
+    public function format(Result $result, Renderer $renderer, array $templates): array;
 }