Add backward compat APIs (#14427)

### What problem does this PR solve?

Add backward compat APIs:

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

test/testcases/test_web_api/test_file_app/test_file_routes_unit.py

@@ -259,7 +259,7 @@ def test_list_files_validation_error(monkeypatch):
     module = _load_file_api_module(monkeypatch)
     monkeypatch.setattr(module, "validate_and_parse_request_args", lambda _request, _schema: (None, "bad args"))
 
-    res = module.list_files("tenant1")
+    res = _run(module.list_files("tenant1"))
     assert res["code"] == 400
     assert res["message"] == "bad args"
 
@@ -330,8 +330,8 @@ def test_download_falls_back_to_document_storage(monkeypatch):
 def test_parent_and_ancestors_use_new_routes(monkeypatch):
     module = _load_file_api_module(monkeypatch)
 
-    parent_res = module.parent_folder("tenant1", "file1")
-    ancestors_res = module.ancestors("tenant1", "file1")
+    parent_res = _run(module.parent_folder("tenant1", "file1"))
+    ancestors_res = _run(module.ancestors("tenant1", "file1"))
 
     assert parent_res["code"] == 0
     assert parent_res["data"]["parent_folder"]["id"] == "parent1"

test/testcases/test_web_api/test_system_app/test_apps_init_unit.py

@@ -79,6 +79,10 @@ def _load_apps_module(monkeypatch):
     api_utils_mod.server_error_response = _server_error_response
     monkeypatch.setitem(sys.modules, "api.utils.api_utils", api_utils_mod)
 
+    backward_compat_mod = ModuleType("api.apps.backward_compat")
+    backward_compat_mod.register_backward_compat_routes = lambda _app: None
+    monkeypatch.setitem(sys.modules, "api.apps.backward_compat", backward_compat_mod)
+
     module_name = "test_apps_init_unit_module"
     module_path = repo_root / "api" / "apps" / "__init__.py"
     spec = importlib.util.spec_from_file_location(module_name, module_path)