Audit #1 – Share a single file – Accordions have no visible focus

[marcus-herrmann]

Connected to Audit 1, see #4300
1.5 Share a single file , URL: https://ocis-a11y.owncloud.works/#/files/list

Issue

The accordions for "Personen" and "Links" inside the "add people" dialog can be operated with keyboard only (activation by SPACE key), but don't have a focus style.

Remediation

Supply focus style for button part of accordion in its focus state.

[pascalwengerter]

Closing this since #5018 is merged and we're waiting for feedback (and will open new tickets with the requested changes from the a11y audit)