Added registration with ZKA (https://www.hbci-zka.de/)

German banks soon require the application to be registered with ZKA in
order to use the their FinTS interface.

This implements the necessary functionality to be in line with the
requirements.

Backported to 4.8

(cherry picked from commit c1d97f88cc88893a0a4b83df78fccefea71e3ed0)