Chat jobs should be created asynchronously
With !5312 (merged) merged we no longer rely on a build ID to produce a response message. This means that we can create the pipeline asynchronously using Sidekiq, preventing us from hitting the 3 second Slack timeout. This basically involves the following steps:
- Perform some very basic validation in the request (whatever would be necessary to schedule the job)
- Schedule the Sidekiq job
- Respond with an empty message as we do now
Should the Sidekiq job fail it should send a message back to the Slack response URL as we do now in the event of .e.g build failures.