Implement network scanning using the standard zigpy interface

[puddly]

https://github.com/zigpy/zigpy/pull/1461

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 66.66667% with 9 lines in your changes missing coverage. Please review.

Project coverage is 98.88%. Comparing base (ccb3afd) to head (04550f1).

Files	Patch %	Lines
bellows/zigbee/application.py	20.00%	8 Missing :warning:
bellows/ezsp/__init__.py	94.11%	1 Missing :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##              dev     #648      +/-   ##
==========================================
- Coverage   99.10%   98.88%   -0.23%     
==========================================
  Files          50       50              
  Lines        3468     3483      +15     
==========================================
+ Hits         3437     3444       +7     
- Misses         31       39       +8     

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