fix: align array_has null buffer for scalar

[comphead]

Which issue does this PR close?

• Closes bug: array_has fails on null buffer union #17263 .

Rationale for this change

• Error occurred in BooleanArray::new() when comparing nested arrays (arrays of arrays)
• Root cause: Null buffer length mismatch in scalar-to-array comparisons

What changes are included in this PR?

• Fixed Length Mismatch: Null buffers now correctly match result array length
• Proper Null Propagation: Null scalars correctly propagate to entire result
• Combined Cases: (false, false) | (true, true) use same logic
• Clear Intent: filter(|nulls| !nulls.is_valid(0)) clearly shows null scalar check

Are these changes tested?

Are there any user-facing changes?

[alamb]

Thank you @comphead -- this fix makes sense to me. I have some small test suggestion but otherwise this looks good to me

[alamb]

This panics for me locally without the fix:

> select array_contains(a, b) from '/tmp/t.parquet';

thread 'main' panicked at /Users/andrewlamb/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/arrow-array-56.0.0/src/array/boolean_array.rs:91:13:
assertion `left == right` failed
  left: 2
 right: 1
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

[alamb]

I recommend we also test with array_contains (b, a) as well to covert the other argument order

[comphead]

Sorry @alamb I'm not sure I'm following, the reverse order would violate array_has function signature.

Error during planning: Failed to coerce arguments to satisfy a call to 'array_has' function: coercion from [List(Field { name: "item", data_type: Boolean, nullable: true, dict_id: 0, dict_is_ordered: false, metadata: {} }), List(Field { name: "item", data_type: List(Field { name: "item", data_type: Boolean, nullable: true, dict_id: 0, dict_is_ordered: false, metadata: {} }), nullable: true, dict_id: 0, dict_is_ordered: false, metadata: {} })] to the signature ArraySignature(Array { arguments: [Array, Element], array_coercion: Some(FixedSizedListToList) }) failed No function matches the given name and argument types 'array_has(List(Field { name: "item", data_type: Boolean, nullable: true, dict_id: 0, dict_is_ordered: false, metadata: {} }), List(Field { name: "item", data_type: List(Field { name: "item", data_type: Boolean, nullable: true, dict_id: 0, dict_is_ordered: false, metadata: {} }), nullable: true, dict_id: 0, dict_is_ordered: false, metadata: {} }))'. You might need to add explicit type casts.

[alamb]

Sorry -- I was just noticing in the code that it has two code paths when left and right are constants, but this query only exercises one of the paths, I think