Purge entity and device registries when importing lcn from configuration.yaml (#54266)

* Identify LCN orphans in entity registry and device registry and remove them

* Fix typing issues

* Revert "Fix typing issues"

This reverts commit eccd067b3b5f23135e6c8a79d25f7f2cbc2d0ae9.

* Fix removal of devices which do not belong to given config_entry

* Use helper for getting entities for config_entry

* Rename variable

tests/components/lcn/test_config_flow.py

@@ -7,6 +7,8 @@ import pytest
 from homeassistant import config_entries, data_entry_flow
 from homeassistant.components.lcn.const import CONF_DIM_MODE, CONF_SK_NUM_TRIES, DOMAIN
 from homeassistant.const import (
+    CONF_DEVICES,
+    CONF_ENTITIES,
     CONF_HOST,
     CONF_IP_ADDRESS,
     CONF_PASSWORD,
@@ -24,6 +26,8 @@ IMPORT_DATA = {
     CONF_PASSWORD: "lcn",
     CONF_SK_NUM_TRIES: 0,
     CONF_DIM_MODE: "STEPS200",
+    CONF_DEVICES: [],
+    CONF_ENTITIES: [],
 }