Zigbee2mqtt: Improve device pairing

[Koenkk]

Some devices are hard to pair, this should be improved. This issue is created in order to gather the points of improvement.

• Xiaomi devices are hard to pair because the modelId can sometimes not be retrieved via the simpleDesc request (e.g. #1391). However, they also report the modelId through a genBasic attReport message. We should use this message and take the modelId from it when it's not present in database.db yet. E.g. debug: Received zigbee message of type 'attReport' with data '{"cid":"genBasic","data":{"65281":{"1":3045,"3":30,"4":424,"5":184,"6":[0,0],"10":12142,"100":1},"modelId":"lumi.sensor_magnet.aq2"}}' of device 'undefined' (0x00158d000252b225) of endpoint 1

[ReneHonig]

that would be great, I often have great difficulty pairing the Xiaomi devices for the reasons stated above. Once they are paired, I find them very reliable with very clever battery management.

[tb-killa]

This improvement would be for all devices to fix this issue too: https://github.com/Koenkk/zigbee2mqtt/issues/1378

[Koenkk]

Implemented in the dev branch!