Set initial token to head when all contained Event Handling Components of a Streaming Event Processor disallow replays

[smcvb]

Feature Description

The current default for Sagas backed by a StreamingEventProcessor (SEP) is to set the initial TrackingToken to the head of the stream in the absence of configuration customization.
Although helpful, we can set a more reasonable approach concerning where a SEP should start processing based on any Event Handling Component (EHC) it deals with.
Namely, when all EHCs disallow replay behavior, it would be reasonable to default the TrackingToken to the head of the stream (i.o. the tail of the stream).

Current Behaviour

Axon Framework's current behavior around initial TrackingTokens for Sagas backed by StreamingEventProcessors is as follows:

1. When there is no configuration customization, the TrackingToken defaults to the head of the stream.
2. When there is configuration customization, the framework does nothing.

Wanted Behaviour

Set the initialTrackingToken to the head of the stream when all EHCs of a Streaming Event Processor disallow replays.
And, in the absence of other user customization, of course.

Possible Workarounds

None.