New endpoint to reset notification status

Current idea:

• New endpoint /Reset_notification_status that resents the status column to ready for the available patients.
• Update the check for available data so that the data to be shared is checked as well

Alternative solution would be to add a new parameter to the /Start_pipeline endpoint, e.g. re-notify which works similarly as the revalidate parameter but for the Notify-Einstein step. Maybe this solution is cleaner and does not need to have an additional endpoint. @philip.krauss @maximilian.pickl What's your opinion on that?