check accessibility, e.g. screenreader notification on result change

https://flow.sbb.ch/browse/SBBCH-16071

translated:

As a user, I would like to be able to use the search function at any time (and no matter where I am on the website) so that I can find the information I need quickly and efficiently.

• The finished SBB (Lyne) components are integrated
• When the user clicks the search link in the header, the search overlay opens
• The overlay can be closed again at any time by clicking on the close button
• The tracking is implemented according to the specification
• End-2-End test to verify search
• The implementation can be reused via shared library.

Out of scope:

• Display of small preview images (see screenshot).

Specification:
https://confluence.sbb.ch/pages/viewpage.action?pageId=2107481446

Design
https://www.figma.com/file/0bciMRes4pYK7z6jGqZ3RE/01%3A-Design-%E2%80%93-Home-2.0?type=design&node-id=3248%3A256162&t=ikNlweGwqnkOhsPo-1