Breadcrumbs > Support sub-levels for native CSS nesting

### Description

For [native CSS nesting](https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_nesting/Using_CSS_nesting), the breadcrumbs currently only show the top-level:


### Use case/motivation

_No response_

### Related issues

_No response_

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

No

Reproduce the issue in Apache NetBeans using native CSS nesting and inspect the editor's breadcrumb behavior and related implementation. Done means breadcrumbs display each nested CSS level instead of only the top-level entry; add coverage for the nested case if the existing breadcrumb tests provide a suitable location.

Written by the indexing model from the issue text.