Support for channel_id in Webhook-Triggered Journeys

Business problem
When triggering a Journey via webhook, it’s currently not possible to pass a channel_id. As a result, the Journey can’t determine which channel to use for sending messages.
 The only exceptions at the moment are:

• WhatsApp templates

• Actions like HTTP calls that don’t require a channel or ticket context

Wished result
The possibility to include a channel_id in the webhook payload, so any messaging action (email, SMS, etc.) can be executed correctly.

Why this matters
This would allow us to trigger fully omnichannel Journeys from external systems, opening up a lot more automation use cases in real life.