Add filterableAttributes syntax API to settings

[kumarUjjawal]

Pull Request

Related issue

Fixes #660

What does this PR do?

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• [x] Does this PR fix an existing issue, or have you listed the changes applied in the PR description (and why they are needed)?
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Summary by CodeRabbit

• New Features

  • Filterable attributes now accept either simple attribute names or richer settings with feature modes.
  • Retrieval and update operations support the mixed-syntax representation.

• Backward Compatibility

  • Existing simple-name workflows continue to work and are automatically mapped to the new format.

• Documentation / Tests

  • Examples and tests updated to demonstrate mixed-syntax usage.

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