Add model to emitted events.

[bjorger]

• I have read and agree to the contributing guidelines.

Is your feature request related to a problem? Please describe.
When calculating the costs of more complex structures (Pipelines, Workflows etc), that can potentially use several different models.

Describe the solution you'd like
it would help to add the model to the event, so it is trackable what part of the structure is responsible for what.

Describe alternatives you've considered
Alternatively, adding the task id to StartPromptEvent and FinishPromptEvent would work for this as well.

Additional context
Add any other context or screenshots about the feature request here.