MFE-6 Use Redis to cache SAP responses

https://jira.usit.uio.no/browse/MFE-6

mfe_ms/backend/routes/dataporten.py

 import json
 import logging
 from datetime import datetime, timedelta
+from http import HTTPStatus
 from typing import Callable, Optional, List, Iterable, Tuple
 from urllib.parse import urlencode
 
@@ -184,7 +185,7 @@ def routes(config: MFEConfig, app: FastAPI, home: Callable):
                 config.auth.dataporten.client_secret,
             ),
         )
-        if token_response.status_code == 400:
+        if token_response.status_code == HTTPStatus.BAD_REQUEST:
             logger.error(
                 "Got 400 Bad Request. Check configuration: %s", token_response.content
             )
@@ -192,7 +193,9 @@ def routes(config: MFEConfig, app: FastAPI, home: Callable):
         token_response.raise_for_status()
 
         if not token_response:
-            raise HTTPException(500, "Failed to get access token")
+            raise HTTPException(
+                HTTPStatus.INTERNAL_SERVER_ERROR, "Failed to get access token"
+            )
 
         oauth_token = auth_client.parse_request_body_response(
             json.dumps(token_response.json())