Extract the storage layer into core

tests/test_startup_db.py

@@ -36,7 +36,7 @@ def _make_hass_mock():
 
 
 def _open_db(path) -> NestQuestDatabase:
-    database = NestQuestDatabase(_make_hass_mock())
+    database = NestQuestDatabase(_make_hass_mock().async_add_executor_job)
     _run(database.open(path))
     return database
 
@@ -44,7 +44,7 @@ def _open_db(path) -> NestQuestDatabase:
 async def _avalid_database(path) -> None:
     """Create a valid, migrated NestQuest database file (async, on the
     running loop, for use inside pytest-asyncio tests)."""
-    database = NestQuestDatabase(_make_hass_mock())
+    database = NestQuestDatabase(_make_hass_mock().async_add_executor_job)
     await database.open(path)
     try:
         await apply_migrations(database)