Entity event setup

[benwainwright]

Validate compliance with https://developers.home-assistant.io/docs/core/integration-quality-scale/rules/entity-event-setup/ and fix any issues

[benwainwright]

Need to understand the synapse code a little more but my initial reading is that synapse is not compliant because it looks like this:

synapse-extension/custom_components/synapse/synapse/base_entity.py

Lines 57 to 75 in 4d6af07

	# Set up event listeners for entity updates and availability changes
	self.async_on_remove(
	self.hass.bus.async_listen(
	self.bridge.event_name("update"),
	self._handle_entity_update,
	)
	)
	self.async_on_remove(
	self.hass.bus.async_listen(
	self.bridge.event_name("health"),
	self._handle_availability_update,
	)
	)
	self.async_on_remove(
	self.hass.bus.async_listen(
	self.bridge.event_name("register"),
	self._handle_registration_event,
	)
	)

Should live in specific lifecycle methods