[Variant] Add variant_to_arrow Struct type support

[sdf-jkl]

Which issue does this PR close?

• Closes [Variant] Add variant_to_arrow Struct type support #9529 .

Rationale for this change

• In a follow up PR, can fix the variant_get TODO:
  

  arrow-rs/parquet-variant-compute/src/variant_get.rs

  Lines 89 to 92 in 3b61796

  	let struct_array = field.as_struct_opt().ok_or_else(|| {
  	// TODO: Should we blow up? Or just end the traversal and let the normal
  	// variant pathing code sort out the mess that it must anyway be
  	// prepared to handle?

• When we know that Struct VariantArray is not shredded can reuse shred_basic_variant

What changes are included in this PR?

• Added StructVariantToArrowRowBuilder builder.
• Moved make_variant_to_arrow_row_builder logic to make_typed_variant_to_arrow_row_builder to reuse by Struct array's inner fields.
• Changed a variant_get test to show that it now handles unshredded Struct VariantArray

Are these changes tested?

• Yes, added test_struct_row_builder_handles_unshredded_nested_structs
• Everything else still works.

Are there any user-facing changes?

No

[sdf-jkl]

@klion26 @codephage2020 @scovich bothering you again... 😄

[scovich]

LGTM with nits, thanks!

[sdf-jkl]

@scovich I've addressed the nits, thanks for the review!

[klion26]

LGMT, thanks for the contribution.

[alamb]

Love it -- thanks @sdf-jkl @klion26 and @scovich