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/utils/file_utils.py

@@ -43,6 +43,7 @@ from ruamel.yaml import YAML
 # Local imports
 from api.constants import IMG_BASE64_PREFIX
 from api.db import FileType
+from common.file_utils import get_project_base_directory
 
 PROJECT_BASE = os.getenv("RAG_PROJECT_BASE") or os.getenv("RAG_DEPLOY_BASE")
 
@@ -51,21 +52,6 @@ if LOCK_KEY_pdfplumber not in sys.modules:
     sys.modules[LOCK_KEY_pdfplumber] = threading.Lock()
 
 
-def get_project_base_directory(*args):
-    global PROJECT_BASE
-    if PROJECT_BASE is None:
-        PROJECT_BASE = os.path.abspath(
-            os.path.join(
-                os.path.dirname(os.path.realpath(__file__)),
-                os.pardir,
-                os.pardir,
-            )
-        )
-
-    if args:
-        return os.path.join(PROJECT_BASE, *args)
-    return PROJECT_BASE
-
 @cached(cache=LRUCache(maxsize=10))
 def load_json_conf(conf_path):
     if os.path.isabs(conf_path):