refactor: enhance CustomComponent class and updates tests (#3201)

* fix: update CustomComponent to use properties for user_id and flow_id

Refactored user_id and flow_id in CustomComponent to use properties for better encapsulation and code clarity

* refactor: update CustomComponent initialization and remove unused imports

Refactored the CustomComponent class to streamline initialization and removed unnecessary import for BaseCallbackHandler

* refactor: update build_custom_component_template to use cc_instance for field order to improve consistency and clarity

* refactor: update user_id parameter in FlowToolComponent to use self.user_id for consistency

* refactor: remove unused _tree attribute and clean up imports in CustomComponent for better code clarity

* refactor: rename CustomComponent to Component for consistency in directory_reader.py import and usage

* refactor: enhance timestamp handling in _timestamp_to_str for better validation and error reporting in message.py

* refactor: preserve async get_file_content_dicts method for backwards compatibility in message.py

* refactor: update function_entrypoint_name to _function_entrypoint_name for consistency in test_custom_component.py

* feat: add client fixture for improved test structure in test_data_components.py

* feat: add unit tests for PromptComponent including template processing and custom fields in test_prompt_component.py

* feat: add dev dependencies for improved testing and development tools in pyproject.toml

src/backend/tests/unit/test_data_components.py

@@ -12,6 +12,11 @@ from httpx import Response
 from langflow.components import data
 
 
+@pytest.fixture
+def client():
+    pass
+
+
 @pytest.fixture
 def api_request():
     # This fixture provides an instance of APIRequest for each test case