[Feature Request]: Allow option for External Notifications to trigger upon a message put in to the channel by the local node/loopback

[vaderj]

Platform

ESP32

Description

For the External Notification module when

external_notification.alert_message: True

it appears to only trigger upon a remote message; it would be great if there was at least an option to have it triggered with the device itself puts a message in the channel.

My specific use case is I want to have an external button which is monitored by the Detection Sensor module, to trigger the External Notification module