creating AbstractDataService class

This is needed to split the CallbackManager into another class.

src/pyDataInterface/data_service/abstract_data_service.py

@@ -0,0 +1,14 @@
+from abc import ABC
+from collections.abc import Callable
+from typing import Any
+
+
+class AbstractDataService(ABC):
+    __root__: "AbstractDataService"
+    _callback_manager: Any
+    """
+    This is a CallbackManager. Cannot type this here as this would lead to a recursive
+    loop.
+    """
+
+    _task_status_change_callbacks: list[Callable[[str, dict[str, Any] | None], None]]