Use asyncio facilities for push server where possible

[starkillerOG]

Make the push server fully async by avoiding using executors when not necessary.

As required by home-assistant/core#64726

[codecov-commenter]

Codecov Report

Merging #1521 (2412cb9) into master (207a053) will decrease coverage by 0.01%.
The diff coverage is 35.48%.

@@            Coverage Diff             @@
##           master    #1521      +/-   ##
==========================================
- Coverage   82.15%   82.13%   -0.02%     
==========================================
  Files         145      145              
  Lines       14161    14164       +3     
  Branches     3416     3416              
==========================================
  Hits        11634    11634              
- Misses       2302     2305       +3     
  Partials      225      225              

Impacted Files	Coverage Δ
miio/push_server/serverprotocol.py	25.75% <0.00%> (ø)
miio/push_server/server.py	24.08% <30.00%> (-0.54%)	⬇️
miio/gateway/alarm.py	47.72% <50.00%> (ø)
miio/gateway/devices/subdevice.py	33.14% <50.00%> (ø)
miio/gateway/gateway.py	44.44% <50.00%> (ø)

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[starkillerOG]

@rytilahti I tested this and everything still works.
This makes a clearer seperation between sync and async code by making all push_server functions async.

Can you merge this?

[starkillerOG]

@rytilahti could you please merge this so I can move allong with PR home-assistant/core#64726?

[rytilahti]

LGTM on surface and it is much better this way, so let's get this merged. Thanks! 👍

[starkillerOG]

@rytilahti thanks a lot!
Could you let me know when a new python-miio version is released so I can continue with the HomeAssistant PR?

[rytilahti]

I'm currently on holidays so I'm not feeling comfortable creating a new release just right now, especially as the current code base contains lot of changes related to #1495 that should be tested also on other devices that I have in my possession.

I'll try to find some time to review the related homeassistant PR soon though :-)