Required fields nested within optional structs can produce nulls if the parent struct is null and fails `is_null` / `is_not_null` evaluation

[hsiang-c]

Apache Iceberg Rust version

v0.10.1

Describe the bug

This bug is reported in Iceberg Java and and fixed in apache/iceberg#14270

To Reproduce

No response

Expected behavior

No response

Willingness to contribute

None