Refactor entitlement post/push

There is now a v1 / v2 version of entitlement post / push.

We should finish the transition to v2 for everything, or perhaps as a first step separate them (and only share outbox).

Ideas:
- `:outbox/type :entitlement-push` could be the new one instead of having a type in the parameters/value.
- implement entitlement push of v1 type i.e. basic in the config.
- deprecate v1 type / config keys

Start by locating the v1 and v2 entitlement post/push entry points, their configuration keys, and the shared outbox handling. Compare how the two versions represent entitlement types and decide whether the transition should separate them first or complete the move to v2. Done means the chosen transition is implemented, v1 behavior/configuration is addressed, and the old type or keys are deprecated where applicable.

Written by the indexing model from the issue text.