Migrate from mkdocs-awesome-pages-plugin to mkdocs-awesome-nav

Description

The mkdocs-awesome-pages plugin has been renamed to mkdocs-awesome-nav.

Tasks

• Upgrade MkDocs dependencies (somehow Renovate is still not handling this).
• Switch from from mkdocs-awesome-pages-plugin to mkdocs-awesome-nav.
• Handle the breaking change: the default configuration file name is now .nav.yml instead of .pages. This involves coordination with downstream projects.