Skip write-only properties for miot status requests

[rytilahti]

This PR changes get_properties_for_mapping to ignore write-only properties for requests.
The requests will also now only contain only the expected keys (did, siid, piid) even if the mapping defines some extras.

Fixes #1376

[codecov-commenter]

Codecov Report

Merging #1525 (925aa13) into master (13d6f4a) will increase coverage by 0.02%.
The diff coverage is 76.92%.

@@            Coverage Diff             @@
##           master    #1525      +/-   ##
==========================================
+ Coverage   82.14%   82.17%   +0.02%     
==========================================
  Files         145      145              
  Lines       14156    14176      +20     
  Branches     1606     3419    +1813     
==========================================
+ Hits        11629    11649      +20     
+ Misses       2302     2299       -3     
- Partials      225      228       +3     

Impacted Files	Coverage Δ
miio/miot_device.py	88.15% <76.92%> (+6.61%)	⬆️
miio/push_server/server.py	24.08% <0.00%> (-0.54%)	⬇️
miio/devicestatus.py	93.93% <0.00%> (ø)
miio/gateway/alarm.py	47.72% <0.00%> (ø)
miio/push_server/serverprotocol.py	25.75% <0.00%> (ø)
...integrations/airpurifier/zhimi/airpurifier_miot.py	81.73% <0.00%> (ø)
...io/integrations/vacuum/dreame/dreamevacuum_miot.py	74.61% <0.00%> (+0.23%)	⬆️
miio/airqualitymonitor.py	84.16% <0.00%> (+0.40%)	⬆️

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