[FE] Improve accessibility

[thogebati]

User story

1. As a disabled person
2. I want / need a accessible web app
3. So that I can use it

Acceptance criteria

• improve accessibility of web app, so that it can for example be used with a screen reader

Definition of done (DoD)

• Work products are uploaded to the Github repository and merged to the main branch
• If necessary, the bill of materials section of the planning documents is updated
• Code/feature passes suited tests
• Code is peer-reviewed
• Help documentation (README) is updated
• Fits into our architecture, where possible

DoD general criteria

• Feature has been fully implemented
• Feature has been merged into the mainline
• All acceptance criteria were met
• Product owner approved features
• All tests are passing
• Developers agreed to release