fix: ensure nullable binary arrays return boxed type arrays instead of Object[]

[kishansinghifs1]

Summary

BinaryStreamReader.readArrayItem used Object.class as the element type for all nullable array columns, so Array(Nullable(Float64)) returned Object[] instead of Double[]. This splits the nullable check from the Variant/Dynamic/Geometry fallback and derives the correct boxed wrapper class via getObjectClass(). Added unit test to verify the component type is Double.class for Array(Nullable(Float64)).

Closes : #2846

Checklist

Delete items not relevant to your PR:

• Closes BinaryStreamReader.ArrayValue wrong return type #2846
• Unit and integration tests covering the common scenarios were added
• A human-readable description of the changes was provided to include in CHANGELOG
• For significant changes, documentation in https://github.com/ClickHouse/clickhouse-docs was updated with further explanations or tutorials

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[chernser]

@kishansinghifs1

Thank you for the contribution!

I will review next week.

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[kishansinghifs1]

Hiii @chernser,
thank you for the opportunity ,
no worries.