Integration with API AuthenticationServices

[maximusVII]

With iOS 12, Apple introduced an API called authenticationServices. This would allow password autofill on OS level.
It would be great if the app could communicate with the newly introduced API.

See details:
https://developer.apple.com/documentation/authenticationservices

[kegesch]

I already had a look into this new API. And commented under #4.
This will definetly be implemented, but probably not for version 1.0.

Also i have actually no experience with Swift. So i would appreciate any help to implement this.