use muc-patternlab-vue library

[itgkarl]

In the meantime there is an internal patternlab project, providing buttons ect. with the right styling as vue-components.
It should be evaluated, if we could use those components instead of maintaining a copy of the css in this project.

[eidottermihi]

its no longer "internal", but already public:

• https://github.com/it-at-m/muc-patternlab-vue
• Docs: https://it-at-m.github.io/muc-patternlab-vue/guide/