Progress bar for screenreader users

[matthilo96]

Is your feature request related to a problem? Please describe.
Currently, screenreader users cannot use the progress bar.

Describe the solution you'd like
Users can identify the number of steps in the process, the current step, and completed steps.
e.g. „Schritt 1 von 4: Leistung – erledigt“. / Aktueller Schritt Schritt 2 von 4: Termin