Move alert constants into const module (#80170)

Co-authored-by: epenet <6771947+epenet@users.noreply.github.com>

homeassistant/components/alert/const.py

@@ -0,0 +1,19 @@
+"""Constants for the Alert integration."""
+
+import logging
+from typing import Final
+
+DOMAIN: Final = "alert"
+
+LOGGER = logging.getLogger(__package__)
+
+CONF_CAN_ACK = "can_acknowledge"
+CONF_NOTIFIERS = "notifiers"
+CONF_SKIP_FIRST = "skip_first"
+CONF_ALERT_MESSAGE = "message"
+CONF_DONE_MESSAGE = "done_message"
+CONF_TITLE = "title"
+CONF_DATA = "data"
+
+DEFAULT_CAN_ACK = True
+DEFAULT_SKIP_FIRST = False