Localize notification_utils to the API

This changeset pulls in all of the notification_utils code directly into the API and removes it as an external dependency.  We are doing this to cut down on operational maintenance of the project and will begin removing parts of it no longer needed for the API.

Signed-off-by: Carlo Costino <carlo.costino@gsa.gov>

tests/app/celery/test_tasks.py

@@ -7,8 +7,6 @@ import pytest
 import requests_mock
 from celery.exceptions import Retry
 from freezegun import freeze_time
-from notifications_utils.recipients import Row
-from notifications_utils.template import PlainTextEmailTemplate, SMSMessageTemplate
 from requests import RequestException
 from sqlalchemy.exc import SQLAlchemyError
 
@@ -39,6 +37,8 @@ from app.enums import (
 from app.models import Job, Notification
 from app.serialised_models import SerialisedService, SerialisedTemplate
 from app.utils import DATETIME_FORMAT
+from notifications_utils.recipients import Row
+from notifications_utils.template import PlainTextEmailTemplate, SMSMessageTemplate
 from tests.app import load_example_csv
 from tests.app.db import (
     create_api_key,