Add firmware update entity to IronOS integration (#123031)

homeassistant/components/iron_os/__init__.py

homeassistant/components/iron_os/coordinator.py

homeassistant/components/iron_os/entity.py

homeassistant/components/iron_os/manifest.json

homeassistant/components/iron_os/number.py

homeassistant/components/iron_os/sensor.py

homeassistant/components/iron_os/update.py

requirements_all.txt

requirements_test_all.txt

tests/components/iron_os/conftest.py

tests/components/iron_os/snapshots/test_update.ambr

tests/components/iron_os/test_update.py