Configuring infrastructure subscriptions in a replay context

[MrHash]

At the moment domain events can be replayed on a special replay channel, which can generate infrastructure events such as a ProjectionCreatedEvent. For handling other configurable infrastructure concerns such as sending emails, we cannot configure a handler to be aware of the replay context.

In order to solve this problem, we could use a replay environment modifier, where domain events are distributed on the standard domain events channel, and much finer control of infrastructure handling is possible. This means we can also remove the replay channel concept.