Implement quirks v2 reporting config, optimize discovery

[TheJulianJES]

Proposed change

This implements quirks v2 reporting_config in ZHA. The quirks v2 processing for ZCL_INIT_ATTRS is also optimized to not copy ZCL_INIT_ATTRS for every entity metadata object.

A test is also added that actually checks the existing ZCL_INIT_ATTRS code and new code:

• that it doesn't modify the original ZCL_INIT_ATTRS class variable, affecting other cluster handler instances
• that ZCL_INIT_ATTRS are correctly set (and doesn't contain attributes also in REPORTING_CONFIG)
• that REPORT_CONFIG is correctly set
• that the cluster handler is claimed when reporting_config is set, thus binding it during ZHA device configuration

Additional information

Supersedes:

• Support configuration of entity reporting for V2 quirks #254

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.58%. Comparing base (e6a01cf) to head (6838b37).
Report is 6 commits behind head on dev.

Additional details and impacted files

@@            Coverage Diff             @@
##              dev     #363      +/-   ##
==========================================
- Coverage   96.58%   96.58%   -0.01%     
==========================================
  Files          61       61              
  Lines        9499     9512      +13     
==========================================
+ Hits         9175     9187      +12     
- Misses        324      325       +1     

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[TheJulianJES]

This PR is ready IMO. It's also well-tested to verify that the existing ZCL_INIT_ATTRS ch class variable isn't screwed up.
If there are too many comments, we can remove some. Others are crucial though if you're looking at this for the first time.