[api] Support to optional parameters on ESPHome actions called from Home Assistant

[edwardtfn]

Component name

api

Link to component documentation on our website

https://esphome.io/components/api/

Describe the enhancement

Currently, when ESPHome publishes an action with specific parameters, all those parameters are required when Home Assistant is calling that action, otherwise the call will fail.
This makes harder to manage improvements, as additional parameters would require existing calls to be updated. Also, in some cases not all parameters may be required (there are lots of examples in Home Assistant, like light.turn_on).
I don't want to go on the direction of a solution, but would be fine either to have a flag when a parameter is not provided or, probably easier, to work with a default value for parameters that are optional.

Use cases

This would make easier evolving system without requiring users to rebuild their existing calls.
Also, on my specific project with NSPanel, I need 2 different actions when calling pages, as some pages requires an entity_id to be shown (like a light page), while some pages (like home) aren't connected to entities and therefore wouldn't require any parameter.
With the optional parameters I would be able to reduce one action and with this reduce memory consumption.
I could list lots of other cases like this. 😉

Anything else?

No response

[github-actions[bot]]

🏷️ I've automatically added the component: api label to help categorize this feature request.