Flip current session and cookie value overriding from identity resolver

[ollieread]

Currently, the identity resolvers that deal with the URL or other parts of a request that would affect the session or a cookie, set those values through the OverridesCookieSettings trait in the ServiceOverride::setup() method.

This is less than ideal, and should ideally be flipped. There needs to be a mechanism by which service overrides can get relevant details from identity resolvers, without identity resolvers having to know of the service overrides.

Perhaps interfaces or attributes?