Publish github app to github marketplace

[Gregory-Pereira]

I would like us to publish the instructlab-bot-<user_name> app to the Github marketplace so its a 1 click install. We could also fit #230 into this, by structuring the webhook information into application, but this requires a little rearchitecting. The app could have its static webhook address be set to route the webhook events through a Load Balancer and set up some tables that will identify which requests get routed where, ex: PR 2 was created on worker 1 and generate-5 was ran on worker 2, etc, which would remove this manual step from the process. This would still require some configuration I think, it would not be exactly a 1 click solution, but I think it is both more scalable and a better UX