Add ability to push event to a SubscriptionModel out-of-band

[johanhaleby]

It can be useful to allow pushing events to (certain?) subscription models. For example for recurring events (TenHoursPassedEvent) and integration events.

[johanhaleby]

Maybe we actually shouldn't be able to do this. Or at least not directly push such an event to SM. Maybe we should require the event to be converted to a command, then you can publish it normally. For example, TenHoursPassedEvent could be translated to what we want to happen after these ten hours have passed, such as RemoveIdlingPlayerFromGameCommand.