Add routing information to Runner Tokens

Overview

In Update TokenAuthenticatable with routable infor... (#486946 - closed) we extended TokenAuthenticatable so that we can add routing information to it. We need to add routing information to the Runner Authentication Token so that we can route the request to the correct Cell.

We need to add the following routing information to Runner tokens:

• g: Owner Namespace ID (owner_runner_namespace.namespace_id.to_s(36))
• u: Creator (User) ID (creator_id.to_s(36))
• c: Cell ID (Settings.cell[:id]&.to_s(36))

All this information is going to be base64 encoded so the HTTP router will decode it as explained in https://handbook.gitlab.com/handbook/engineering/architecture/design-documents/cells/routable_tokens/.