[C++] IPC: validate batch schema equals stream schema in debug mode

This came up in a Flight/Flight SQL demo a colleague was working on; it was possible to write a batch with a differing schema than what was stated for the stream, which would lead to a decoding failure on the other side. It might be useful in DEBUG mode to DCHECK this and fail-fast.

The error message could also be improved; `ArrayLoader.GetBuffer` could at least return the index and the actual # of buffers

**Reporter**: [David Li](https://issues.apache.org/jira/browse/ARROW-16625) / @lidavidm

_{**Note**: *This issue was originally created as [ARROW-16625](https://issues.apache.org/jira/browse/ARROW-16625). Please see the [migration documentation](https://github.com/apache/arrow/issues/14542) for further details.*}

Start by tracing the IPC batch and stream schema handling described for the Flight/Flight SQL demo, then inspect ArrayLoader.GetBuffer, which the issue names explicitly. Done means debug-mode validation fails fast when batch and stream schemas differ, and the buffer error reports the index and actual buffer count.

Written by the indexing model from the issue text.