[Orchestrator] - New endpoint notifications in order to manage notifications tasks

Here below a list of step by step requirements for the above concept to be feasible:

• A new endpoint “notifications”
• Making sure the tasks notification is well processed based on its cycle of repetition.
• Treat every subtasks and send the notification if required + update status of the subtask.
• Remove the subtasks if no attributes listed match the alert specified in the main task.

A design document can be found about notifications here