feat: Home Assistant: Discover temperature sensor for thermostats

[burmistrzak]

According to the HA folks, it's current best practice to expose/discover an additional temperature sensor for each thermostat because the current_temperature attribute of climate entities is not kept for long-term statistics.

By implementing this using the homeassistant.ts extension, we avoid exposing fake sensors to other ecosystems while still improving the UX for HA users. 😊

Fixes #29686

[burmistrzak]

This probably deserves a unit test.
We need to make sure that local_temperature is correctly discovered as an additional sensor for different kind of thermostats.

There's also a small number of devices that already do expose local_temperature outside of a climate feature, so this case should be covered as well.

[Koenkk]

Could you extend

zigbee2mqtt/test/extensions/homeassistant.test.ts

Line 981 in 3a49c95

it("Should discover thermostat devices", () => {

?

[burmistrzak]

@Koenkk AFAIK, there's no mock device in tests that already exposes climate and local_temperature or temperature.

Currently, my test only covers the most common case, i.e. discover local_temperature of climate as an additional temperature sensor if no separate sensor named local_temperature or temperature is exposed.

Is this good enough?

[Koenkk]

yes, thanks!