restructure and improve gateway subdevices (#700)

* restructure and improve gateway subdevices

* Update gateway.py

* fix cli

* black formatting

* filter out gateway

* better error handeling

* common GatewayDevice class for __init__

* remove duplicate "gateway" from method name

* use device_type instead of device_name for mapping

* add comments

* use DeviceType.Gateway

Co-authored-by: Teemu R. <tpr@iki.fi>

* Update gateway.py

* improve discovered info

* fix formatting

* better use of dev_info

* final black formatting

* process revieuw

* generilize properties of subdevices

* Subdevice schould not derive from Device

* simplify dataclass props for subdevices

* optimization

* remove empty checks and futher simplify dataclass

* Update gateway.py

* add back SensorHT

* add back Empty response

* black formatting

* add missing docstrings

* fix except

* fix black

* Update pyproject.toml

* Update pyproject.toml

* fix dataclasses

* replace dataclasses by attr

* add get_local_status command

* remove local.status again

Co-authored-by: Teemu R. <tpr@iki.fi>