feat: migrate GlBadge

BREAKING CHANGE: Remove GlBadge's router link and nuxt link related
props.

* Migrates GlBadge so it does not make use of Bootstrap Vue's
BBadge anymore.
* Still uses the BLink component if link props are provided.
* Specs are added for the additional functionality.
* Docs for the badge include information about the link badge now.
* Include link badge styling for disabled case.
* Update GlBadge default story.
* Removes vendored BBadge code.