Merge branch 'feature/ISTWCMS-5635-migrate-site-footer' into '1.0.x'

src/patterns/01-core/mixins/_accessiblity.scss

src/patterns/03-layouts/site-footer/_site-footer.scss

src/patterns/03-layouts/site-footer/site-footer.twig

src/patterns/04-components/_index.scss

src/patterns/04-components/menu/_menu.scss

...tterns/04-components/menu/menu--social/_menu--social.scss

...atterns/04-components/menu/menu--social/menu--social.twig

...patterns/04-components/menu/menu--social/menu--social.yml

src/patterns/04-components/menu/menu.twig

src/patterns/04-components/menu/menu.yml

.../social-media/social-media--icon/_social-media--icon.scss

...s/social-media/social-media--icon/social-media--icon.twig

...ts/social-media/social-media--icon/social-media--icon.yml