DS - optimize accessibility

[Bruno0221]

Value proposition

As a User I want the App to adhere to all A11y Best Practices In order to use the App regardles of different capabilities

Acceptance criteria

• [ ] App gets a 100 in google lighthouses Accessibility score

Tasks

• [x] Create new branch US_optimize-accessibility
• [x] change colors to have a higher contrast in following elements:
  • [x] --font-body
  • [x] ArrowButton, ArrowLink and PrimaryButton components
  • [x] category tags
• [x] restucture EventPreview and CategoryCard component so that the li Element is the direct child of the ul
• [x] move Head component with document title from _document.js to app.js
• [x] Like Icon gets appropriate aria label
• [x] check aria-role for evnts description in EventDetail component
• [x] change html language to german
• [x] change alt texts to german

[Lea-Mentz]

App gets a 95 score in google lighthouse.