Use enum value when looking up entity class by entity device_class

[prairiesnpr]

We have two definitions for SensorDeviceClass.

zha.application.platforms.sensor.const.SensorDeviceClass and zigpy.quirks.v2.homeassistant.sensor.SensorDeviceClass

Quirks will import from zigpy and the current logic would fail to match. This works for both enums and modifies the tests to ensure we test both enums.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.31%. Comparing base (3d34a30) to head (d3ac280).
Report is 1 commits behind head on dev.

Additional details and impacted files

@@           Coverage Diff           @@
##              dev     #248   +/-   ##
=======================================
  Coverage   96.31%   96.31%           
=======================================
  Files          61       61           
  Lines        9366     9366           
=======================================
  Hits         9021     9021           
  Misses        345      345           

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