Event driven sensor updates

[yxkrage]

Issue

When the select option Garo Wallbox is changed to e.g. Not Available for Charging from HomeAssistant it can take up to 30 seconds until the sensor (sensor.garo_wallbox) is updated.

Solution

This code fix ensures that the status (and all other sensors' values) are updated immediately when the option is changed in HomeAssistant.

[sockless-coding]

I don't think the event handling is part is needed, it should already be handled by the coordinator.
The main problem is that set_option is calling the api_client directly, it should have a coordinator method that also calls the async_request_refresh.

[sockless-coding]

This has been superseded by #60