Restore tuple-based ProxyRule config once config-rs is fixed

See discussion at !1640 (comment 2953073) : There is a bug in config-rs that keeps us from using [pattern, action] as the format for our rules for our tor-hsrproxy rules. As a temporary measure we're using "pattern => action" strings instead, but we don't want to do that permanently.

Once config-rs has fixed https://github.com/mehcode/config-rs/issues/464 — ideally, by merging https://github.com/mehcode/config-rs/pull/465 — we should go back to our original code.