Active local task should carry nav-link class

Problem/Motivation

An active local task does not get the bootstrap "nav-link" class, while Bootstrap it self uses the "nav-link" class on active items too. This can be seen in the Bootstrap examples: https://getbootstrap.com/docs/5.1/components/navs-tabs/

Steps to reproduce

Check the active item in a nav tab element in bootstrap5 theme (e. g. the view tab of the node operations when logged in). The view tab is the active tab and it does not get the "nav-link" class, just, the "active and is-active" classes. The other tabs get the "nav-link" class.

Proposed resolution

Add "nav-link" class in preprocess function to active item as well.

Remaining tasks

create a patch

User interface changes

Active tabs will get the bootstrap class "nav-link" and therefore behave as expected from vanilla bootstrap.

API changes

none

Data model changes

none