Separate example policies from the main (i.e. router) policy

[anderseknert]

Users of this hook likely will want to provide their own policies rather than the examples we provide. I think we should move these to a new examples directory where we can have one subdirectory for the templates (as suggested by @tsandall elsewhere), and another for policy.

Remaining in the policy directory should only be main.rego and authz.rego, plus a subdirectory for the tests / helpers.

[anderseknert]

The templates directory is now moved to examples/templates. As for the policies, I think what we have now is fine. Users are likely going to pick and choose either way, and it's well documented how the router logic works, so they'll likely want to add that themselves.