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>

app/serialised_models.py

@@ -4,16 +4,16 @@ from threading import RLock
 
 import cachetools
 from flask import current_app
-from notifications_utils.clients.redis import RequestCache
-from notifications_utils.serialised_model import (
-    SerialisedModel,
-    SerialisedModelCollection,
-)
 from werkzeug.utils import cached_property
 
 from app import db, redis_store
 from app.dao.api_key_dao import get_model_api_keys
 from app.dao.services_dao import dao_fetch_service_by_id
+from notifications_utils.clients.redis import RequestCache
+from notifications_utils.serialised_model import (
+    SerialisedModel,
+    SerialisedModelCollection,
+)
 
 caches = defaultdict(partial(cachetools.TTLCache, maxsize=1024, ttl=2))
 locks = defaultdict(RLock)