feat(lib): annotate cookies with what rule was passed (#576)

* feat(lib): annotate cookies with what rule was passed

Anubis JWTs now contain a policyRule claim with the cryptographic hash
of the rule that it passed. This is intended to help with a future move
away from proof of work being the default.

Signed-off-by: Xe Iaso <me@xeiaso.net>

* test(lib): fix cookie storage logic

Signed-off-by: Xe Iaso <me@xeiaso.net>

---------

Signed-off-by: Xe Iaso <me@xeiaso.net>

lib/testdata/rule_change.yaml

@@ -0,0 +1,12 @@
+bots:
+- name: old-rule
+  path_regex: ^/old$
+  action: CHALLENGE
+
+- name: new-rule
+  path_regex: ^/new$
+  action: CHALLENGE
+
+status_codes:
+  CHALLENGE: 401
+  DENY: 403