refactor(backend): Extract Airtable token refresh to shared utility

- Create app/utils/airtable_token_utils.py for token refresh logic
- Update all connectors to use centralized token refresh function
- Affected connectors: airtable, clickup, confluence, discord, jira, notion, slack, teams
- Improves code reusability and maintainability
- No functional changes, pure refactoring

surfsense_backend/app/connectors/airtable_history.py

@@ -12,7 +12,7 @@ from sqlalchemy.future import select
 from app.config import config
 from app.connectors.airtable_connector import AirtableConnector
 from app.db import SearchSourceConnector
-from app.routes.airtable_add_connector_route import refresh_airtable_token
+from app.utils.airtable_token_utils import refresh_airtable_token
 from app.schemas.airtable_auth_credentials import AirtableAuthCredentialsBase
 from app.utils.oauth_security import TokenEncryption