fix: make flow name retrieval efficient (cocoindex-io#414)

Co-authored-by: LJ <[email protected]>

Author: lemorage

python/cocoindex/cli.py

@@ -3,6 +3,7 @@
 from rich.console import Console
 
 from . import flow, lib
+from .flow import flow_names
 from .setup import sync_setup, drop_setup, flow_names_with_setup, apply_setup_changes
 from .runtime import execution_context
 
@@ -20,7 +21,7 @@ def ls(show_all: bool):
     """
     List all flows.
     """
-    current_flow_names = flow.flow_names()
+    current_flow_names = flow_names()
     persisted_flow_names = flow_names_with_setup()
     remaining_persisted_flow_names = set(persisted_flow_names)