feat: A11Y-Improvements

[therobrob]

• standardized focus-indicators
• reworked expander-arrow so that it won't read out by screenreaders
• hide <br> for screenreader
• hide <hr> for screenreader
• updated aria-label for search-input
• updated aria-label for updateDate
• add aria-label for related countries
• add lang-tag for footer-love

I wanted to remove the corners, but i didn't find a solution. I could change a to align-items: center and icon-specs, but then the multi-line items won't look good.

[github-actions]

Hi there! 👋

Thank you for your contribution to the FIP Guide! 🚀
We appreciate your effort in making rail staff travel information more accessible. 🚄

Checklist before merging:

• Added a description to the Pull Request
• Checked the License of new pictures (non-commercial use without attribution)
• Modified content in English
• Modified content in German
• Modified content in French

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[MoritzWeber0]

I like the new focus indicators :)

[therobrob]

@toniarndt if you find more issues regarding a11y, feel free to commit them or comment here :)