#902 - replaced 'final_node_<placeholder>' with 'reference_node_<placeholder>' in methods for scoring of os_state, file_system_state, service state and operating state. This fixed the reward function so it is checked at each step for node operating system state, operating state, file system state and service state.

- Added unit tests.

tests/__init__.py

@@ -0,0 +1,6 @@
+# Crown Copyright (C) Dstl 2022. DEFCON 703. Shared in confidence.
+from pathlib import Path
+from typing import Final
+
+TEST_CONFIG_ROOT: Final[Path] = Path(__file__).parent / "config"
+"The tests config root directory."