Site access updates (#6731)

* Throw error on invalid site access policy

- If ALLOWED_HOSTS is empty, exit
- If CSRF_TRUSTED_ORIGINS is empty, exit
- Closes https://github.com/inventree/InvenTree/issues/6730

* Set parameters for devcontainer

* Update documentation

* Ignore server exit in testing mode

* Add INVENTREE_SITE_URL to CI

* Further CI updates

* Update settings.py

* Unit test updates

* More unit test updates

* Bump API version

* Re-introduce checks in settings.py

- Allow more lenient behaviour in TESTING mode

.devcontainer/docker-compose.yml

@@ -31,6 +31,8 @@ services:
       INVENTREE_DB_USER: inventree_user
       INVENTREE_DB_PASSWORD: inventree_password
       INVENTREE_PLUGINS_ENABLED: True
+      INVENTREE_SITE_URL: http://localhost:8000
+      INVENTREE_CORS_ORIGIN_ALLOW_ALL: True
       INVENTREE_PY_ENV: /home/inventree/dev/venv
 
     depends_on: