OZG-7078 OZG-7202 Add a11y button

alfa-client/apps/admin/src/app/app.component.html

alfa-client/apps/alfa/src/app/app.component.html

alfa-client/libs/common/project.json

alfa-client/libs/common/src/index.ts

...cessibility-button/accessibility-button.component.spec.ts

...ib/accessibility-button/accessibility-button.component.ts

...nt/libs/common/src/lib/build-info/build-info.component.ts

.../icons/accessibility-icon/accessibility-icon.component.ts

...-client/libs/design-system/src/lib/link/link.component.ts

...ion/src/lib/header-container/header/header.component.html

.../src/lib/header-container/header/header.component.spec.ts

alfa-client/libs/navigation/src/lib/navigation.module.ts