feat: attrs integration

[cofin]

Adds attrs support into the ResultConverter mixin. This enables to_schema and schema_dump to natively understand attrs.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 88.35%. Comparing base (0b2749e) to head (b53c668).
⚠️ Report is 124 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #503   +/-   ##
=======================================
  Coverage   88.35%   88.35%           
=======================================
  Files          84       84           
  Lines        5661     5661           
  Branches      728      728           
=======================================
  Hits         5002     5002           
  Misses        441      441           
  Partials      218      218           

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[github-actions]

Documentation preview will be available shortly at https://litestar-org.github.io/advanced-alchemy-docs-preview/503