Support Updates on Crew Executions

[human058382928]

A new endpoint is needed to update a crew execution record. The workflow involves first creating a new crew execution, followed by creating the crew execution steps and linking them to the crew execution ID. Finally, the endpoint should allow updating the record to include the final result and the token count.

Currently the token count is hard coded to 0 and there is not field for the final result in the model/database.