📎 Implement declaration-block-no-duplicate-properties

[togami2864]

Description

Implement declaration-block-no-duplicate-properties

Important

• Please skip implementing options for now since we will evaluate users actually want them later.
• Please ignore handling extended CSS language cases such as sass and less.
• Please skip custom function since we haven't syntax model yet.

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[togami2864]

@chansuke I'm not sure why I can't assign this task, but this issue is yours 😃

And I think it would be better to implement the behavior when 'stylelint's ignore: ['consecutive-duplicates-with-different-syntaxes'] is enabled, as it allows users to adopt the recommended configuration without any further adjustments.