[C++] Unsupported cast using function cast_struct

Casting of structs that were introduced in ARROW-1888 no longer seems to work on the new 9.0.0 release. However, works on the older 8.0.0 release.
I've included the same example given in ARROW-1888 to reproduce the error.

Steps to reproduce:

`arr = pa.array([\\{'a': 1, 'b': None}, \\{'a': 2, 'b': None}])`
`print(arr.type)`
`arr.cast(pa.struct([('a', pa.int64()), ('b', pa.int64())]))`

Expected:

` – is_valid: all not null – child 0 type: int64 [ 1, 2 ] – child 1 type: int64 [ null, null ] `

Actual Results:

`ArrowNotImplementedError: Unsupported cast from struct to struct using function cast_struct`

**Reporter**: [Hyun S](https://issues.apache.org/jira/browse/ARROW-17333)

_{**Note**: *This issue was originally created as [ARROW-17333](https://issues.apache.org/jira/browse/ARROW-17333). Please see the [migration documentation](https://github.com/apache/arrow/issues/14542) for further details.*}

Run the Python reproduction using pa.array and arr.cast with the struct containing a null-only field, then inspect the cast_struct entry point and the ARROW-1888 example. Done means the cast succeeds on the 9.0.0 behavior and produces the expected StructArray with int64 child fields, including null values.

Written by the indexing model from the issue text.