Fix: Properly parse custom array documentation

[numbata]

This PR addresses the issue where grape-swagger-entity was not correctly parsing custom array documentation (e.g., type: 'Array[Object]'), leading to incorrect Swagger schema generation.

The fix introduces a new array_type? method that intelligently identifies various array notations (is_array, type: 'array', or type: 'Array[Object]'). This ensures that the documentation override is correctly recognized and that the generated Swagger schema accurately reflects the intended type.

Part of [#962](https://github.com/ruby-grape/grape-swagger/issues/962)

[grape-bot]

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:warning:	Unless you're refactoring existing code or improving documentation, please update CHANGELOG.md.

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* [#86](https://github.com/ruby-grape/grape-swagger-entity/pull/86): Fix: properly parse custom array documentation - [@numbata](https://github.com/numbata).

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