[DAILY AGS] Implement daily preferences logic

Apply preferences becomes:

# pseudo-code
for delivery_method in delivery_methods:
    if delivery_method == "LIVE":
        Send live email
    if delivery_method == "DAILY"
        time = Fetch daily feed time from Config         
        
        date = today
        if current_time > time #email aggregation as already been sent for today
            date = tomorrow

        Create new entry in table user_daily_notifications: {user_id, notification_id, datetime: time}

More info: https://codimd.web.cern.ch/LtipSj4_RDmBvz3hWJed2Q?view#Option-2