Add `gl-label-link-underline` class fo `text-decoration: underline`
on inner `gl-label-text` and `gl-label-text-scoped` elements so that
they inherit relative color. This ensures scoped labels will have
underline colors that match the text color.

fix(GlLabel): restore text-decoration underline on hover for labels

See merge request gitlab-org/gitlab-ui!4387



Merged-by: Savas Vedova <svedova@gitlab.com>
Approved-by: Jeremy Elder <jelder@gitlab.com>
Approved-by: Savas Vedova <svedova@gitlab.com>
Co-authored-by: sdejonge <sdejonge@gitlab.com>

## [86.7.1](gitlab-org/gitlab-ui@v86.7.0...v86.7.1) (2024-07-11)

### Bug Fixes

* **GlLabel:** restore text-decoration underline on hover for labels ([a4e6f224](gitlab-org/gitlab-ui@a4e6f224))