In split-window mode, highlight brackets of the same block that are in different windows.

### Description

I split the code window into two windows to compare different areas, finding it useful to determine whether the curly brace closing a block in the lower window matches the curly brace opening the block in the upper window.

### Use case/motivation

Useful in debugging and/or refactoring.

### Related issues

_No response_

### Are you willing to submit a pull request?

No

No files, tests, or entry points are named in the issue. Start by locating NetBeans' split-window and bracket-highlighting entry points, then verify that matching opening and closing braces are highlighted when they appear in different windows; done means this behavior works while comparing split editor views.

Written by the indexing model from the issue text.