Add time utils (#10849)

### What problem does this PR solve?

- Add time utilities and unit tests

### Type of change

- [x] Refactoring

---------

Signed-off-by: Jin Hai <haijin.chn@gmail.com>

api/db/services/user_service.py

@@ -24,7 +24,8 @@ from api.db import UserTenantRole
 from api.db.db_models import DB, UserTenant
 from api.db.db_models import User, Tenant
 from api.db.services.common_service import CommonService
-from api.utils import get_uuid, current_timestamp, datetime_format
+from api.utils import get_uuid
+from common.time_utils import current_timestamp, datetime_format
 from api.db import StatusEnum
 from rag.settings import MINIO