fix: Tuple IN null semantics for struct comparisons

[xiedeyantu]

Which issue does this PR close?

• No issue linked yet.

Rationale for this change

This PR corrects IN evaluation for tuple/struct comparisons when a candidate row contains NULL in one or more fields.

For example:

SELECT struct(7521, 30) IN (struct(7521, NULL)) 

now returns NULL instead of false.

This matches standard SQL three-valued logic and aligns DataFusion with PostgreSQL behavior.

What changes are included in this PR?

• Update tuple/struct IN evaluation to preserve null semantics for nested fields
• Add a regression test in datafusion/physical-expr
• Add a sqllogictest case to cover the SQL-level behavior

Are these changes tested?

Yes.

• Unit tests cover the physical expression behavior
• Sqllogictest coverage verifies the SQL-level result

Are there any user-facing changes?

Yes.

Tuple/struct IN now returns NULL when nested NULLs are involved, matching PostgreSQL behavior.

[xiedeyantu]

Hi @alamb , may I ask if this PR of mine is needed?