Add support for `homeassistant.update_entity` to trigger based template sensors

Feature Requests
1

Now that we can define blueprint template sensors , I’m looking for a way to manually trigger a specific template sensor to update.

The only way I’ve come up with is to define a custom event and pass in some kind of event data from an input:

blueprint:
  input:
    name:
        ...
trigger:
  - trigger: event
    event_type: MY_UPDATE_TEMPLATE
      event_data:
        name: !input name
  - trigger: event
    event_type: event_template_reloaded

I think it would be nicer if trigger based template sensors supported homeassistant.update_entity. This way I don’t need to implement a custom event.

Since some trigger template sensors require data, maybe it’s better to have the trigger template sensor opt in to supporting this functionality?

- trigger:
    - trigger: homeassistant # New part
      event: update_entity
    - trigger: event
      event_type: event_template_reloaded

See homeassistant.update_entity called on a trigger-based template sensor results in a "not implemented" error · Issue #140730 · home-assistant/core · GitHub for some more background.