Move 'get_project_base_directory' to common directory (#10940)

### What problem does this PR solve?

As title

### Type of change

- [x] Refactoring

---------

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

api/settings.py

@@ -25,7 +25,7 @@ import rag.utils.infinity_conn
 import rag.utils.opensearch_conn
 from api.constants import RAG_FLOW_SERVICE_NAME
 from api.utils.configs import decrypt_database_config, get_base_config
-from api.utils.file_utils import get_project_base_directory
+from common.file_utils import get_project_base_directory
 from rag.nlp import search
 
 LLM = None