Add humidifier support to homekit (#37207)

* Add humidifier support to homekit

* spell

* dependencies

* lint

* add linked humidity sensor for humidifiers

* Apply suggestions from code review

Co-authored-by: J. Nick Koston <nick@koston.org>

* apply suggestions from code review

* pylint

* Fix tests

* Update homeassistant/components/homekit/type_humidifiers.py

Co-authored-by: J. Nick Koston <nick@koston.org>

* Update tests/components/homekit/test_homekit.py

Co-authored-by: J. Nick Koston <nick@koston.org>

* Apply suggestions from code review

Co-authored-by: J. Nick Koston <nick@koston.org>

* apply suggestions from code review

* lint

* pylint

* push

* test for unavailable linker sensor

* black

* valid values key case

* black

* Update homeassistant/components/homekit/type_humidifiers.py

Co-authored-by: J. Nick Koston <nick@koston.org>

* black

* coverage

* Set current humidity to 0 if linked sensor removed or unavailable

* use last known humidity instead

Co-authored-by: J. Nick Koston <nick@koston.org>

homeassistant/components/homekit/config_flow.py

@@ -47,6 +47,7 @@ SUPPORTED_DOMAINS = [
     "demo",
     "device_tracker",
     "fan",
+    "humidifier",
     "input_boolean",
     "light",
     "lock",
@@ -65,6 +66,7 @@ DEFAULT_DOMAINS = [
     "alarm_control_panel",
     "climate",
     "cover",
+    "humidifier",
     "light",
     "lock",
     "media_player",