Support multiple deCONZ gateways

[Kane610]

Breaking Change:

Description:

In preparation for the soon to be released Conbee 2 and for all users wanting to migrate in an orderly fashion.

• Fix storing of gateways in hass.data
• Fix signalling of reachable gateways
• Fix signalling of new events
• Fix designating master gateway for services
• Fix unload entry
• Fix services handling multiple gateways

Checklist:

• The code change is tested and works locally.
• Local tests pass with tox. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.

If the code does not interact with devices:

• Tests have been added to verify that the new code works.

[pergolafabio]

Where do you see that info about a new conbee?

[Hedda]

@pergolafabio More than one reseller has leaked that "ConBee II" hardware will be released (very soon).

[codecov]

Codecov Report

Merging #22449 into dev will decrease coverage by <.01%.
The diff coverage is 95.12%.

@@            Coverage Diff             @@
##              dev   #22449      +/-   ##
==========================================
- Coverage   93.83%   93.83%   -0.01%     
==========================================
  Files         449      449              
  Lines       36558    36574      +16     
==========================================
+ Hits        34305    34319      +14     
- Misses       2253     2255       +2

Impacted Files	Coverage Δ
homeassistant/components/deconz/sensor.py	95.89% <100%> (ø)	⬆️
homeassistant/components/deconz/const.py	100% <100%> (ø)	⬆️
homeassistant/components/deconz/switch.py	100% <100%> (ø)	⬆️
homeassistant/components/deconz/climate.py	98.18% <100%> (ø)	⬆️
homeassistant/components/deconz/light.py	100% <100%> (ø)	⬆️
homeassistant/components/deconz/deconz_device.py	100% <100%> (ø)	⬆️
homeassistant/components/deconz/binary_sensor.py	91.66% <100%> (ø)	⬆️
homeassistant/components/deconz/cover.py	100% <100%> (ø)	⬆️
homeassistant/components/deconz/scene.py	100% <100%> (ø)	⬆️
homeassistant/components/deconz/config_flow.py	97.77% <90.47%> (-0.19%)	⬇️
... and 1 more

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[Kane610]

@MartinHjelmare I will create a follow up PR to fix your comments, if you plan to review it more, I can ofc wait till you're done.

[MartinHjelmare]

I'm done, thanks.

[Anonym-tsk]

@Kane610 You removed async_step_options from config_flow.py.
How now i can to change allow_clip_sensor and allow_deconz_groups properties?