[C++] Check nullability when validating fields on batches or struct arrays

According to ARROW-15899, it is possible to declare a field non-nullable, associate with data that has nulls, and still pass validation.

Validation should instead fail in such a situation (at least full validation, since computing the null count can be O\(n\)).

**Reporter**: [Antoine Pitrou](https://issues.apache.org/jira/browse/ARROW-15961) / @pitrou
**Assignee**: [Kaouther Abrougui](https://issues.apache.org/jira/browse/ARROW-15961)
#### Related issues:
- [[C++] Parquet writes broken file or incorrect data when nullable=False](https://github.com/apache/arrow/issues/31329) (relates to)
- [[C++] Properly handle non-nullable fields in Parquet reading](https://github.com/apache/arrow/issues/31526) (is related to)
#### PRs and other links:
- [GitHub Pull Request #12706](https://github.com/apache/arrow/pull/12706)

_{**Note**: *This issue was originally created as [ARROW-15961](https://issues.apache.org/jira/browse/ARROW-15961). Please see the [migration documentation](https://github.com/apache/arrow/issues/14542) for further details.*}