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/user/rest.py

@@ -4,7 +4,6 @@ from datetime import datetime
 from urllib.parse import urlencode
 
 from flask import Blueprint, abort, current_app, jsonify, request
-from notifications_utils.recipients import is_us_phone_number, use_numeric_sender
 from sqlalchemy.exc import IntegrityError
 from sqlalchemy.orm.exc import NoResultFound
 
@@ -57,6 +56,7 @@ from app.user.users_schema import (
     post_verify_webauthn_schema,
 )
 from app.utils import url_with_token
+from notifications_utils.recipients import is_us_phone_number, use_numeric_sender
 
 user_blueprint = Blueprint("user", __name__)
 register_errors(user_blueprint)