Event loops have to be closed properly, otherwise pytest will throw a
warning / error. Disconnecting clients and closing the server is
important for that, as well as stopping tasks.
Additionally, I had to add loop_scope parameters to share the event loop
throughout modules which all use the same pydase.Server instance.
- using parse_full_access_path instead of parse_keyed_attribute
- renames get_next_level_dict_by_key to get_container_item_by_key
- replaces ensure_exists and get_nested_value by get_or_create_item_in_container
This allows us to handle access paths like "dict_attr['key'][0].some_attr".
