Add config flow for Nuheat (#32885)

* Modernize nuheat for new climate platform

* Home Assistant state now mirrors the
  state displayed at mynewheat.com

* Remove off mode as the device does not implement
  and setting was not implemented anyways

* Implement missing set_hvac_mode for nuheat

* Now shows as unavailable when offline

* Add a unique id (serial number)

* Fix hvac_mode as it was really implementing hvac_action

* Presets now map to the open api spec
  published at https://api.mynuheat.com/swagger/

* ThermostatModel: scheduleMode

* Revert test cleanup as it leaves files behind.

Its going to be more invasive to modernize the tests so
it will have to come in a new pr

* Config flow for nuheat

* codeowners

* Add an import test as well

* remove debug

homeassistant/generated/config_flows.py

@@ -77,6 +77,7 @@ FLOWS = [
     "netatmo",
     "nexia",
     "notion",
+    "nuheat",
     "opentherm_gw",
     "openuv",
     "owntracks",