Add LocalDataCluster._DEFAULT_VALUES

[TheJulianJES]

Proposed change

This adds a _DEFAULT_VALUES dict to LocalDataCluster, similar to _CONSTANT_ATTRIBUTES.
This allows quirks using LocalDataCluster to set default values that can be overridden, unlike _CONSTANT_ATTRIBUTES.

TODO: Tests

Additional information

There are multiple issues with the current pattern of checking attrid not in self._attr_cache and then using update_attribute:

• Zigpy clears the attribute cache after the quirk is applied, so the update_attribute call essentially did nothing. Appdb loading: https://github.com/zigpy/zigpy/blob/70d15a5dde9adc28c230261d4ac32b7309075415/zigpy/appdb.py#L701-L724
• Zigpy does not populate the attribute cache for custom clusters before the quirk is loaded. Same link as above.
• Zigpy apparently does not save attribute values to the DB that happen in Cluster.__init__ using update_attribute.
  • Zigpy also does not save attribute values on shutdown for any quirked devices: https://github.com/zigpy/zigpy/blob/70d15a5dde9adc28c230261d4ac32b7309075415/zigpy/appdb.py#L433-L441

There's an issue though: The Aqara feeder implementation also uses default values, but it's not a LocalDataCluster. That should be converted and/or we should consider moving this into zigpy's CustomCluster, where the _CONSTANT_ATTRIBUTES also (partly) live already.

In the future, we can also look at making _CONSTANT_ATTRIBUTES, _VALID_ATTRIBUTES, and _DEFAULT_VALUES (only) compatible with ZCLAttributeDef and/or name, instead of just IDs.
I'd do that in a separate PR though and keep the implementations consistent for now.

Checklist

• The changes are tested and work correctly
• pre-commit checks pass / the code has been formatted using Black
• Tests have been added to verify that the new code works
• Device diagnostics data has been attached

[codecov]

Codecov Report

❌ Patch coverage is 81.25000% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 92.29%. Comparing base (40b41de) to head (69cd7f0).

Files with missing lines	Patch %	Lines
zhaquirks/__init__.py	76.92%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##              dev    #4771      +/-   ##
==========================================
- Coverage   92.32%   92.29%   -0.03%     
==========================================
  Files         371      371              
  Lines       12190    12191       +1     
==========================================
- Hits        11254    11252       -2     
- Misses        936      939       +3     

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[TheJulianJES]

We'll need to look into this as well (to clear an attribute). Or maybe have an _UNSUPPORTED_ATTRIBUTES constant in LocalDataCluster and/or CustomCluster as well? It would also help for some Tuya quirks...