Add support for ckWebAuthToken for user authenticated calls

[edorphy]

Investigate how to receive the ASWebAuthenticationSession completion within App Clip

What I've got so far

1. Call the currentUser
2. Get the redirect pass it into ASWebAuthenticationSession
3. Figure out how to hook the session to invoke the app clip user activity or some other mechanism

[edorphy]

I opened up a DTS on this with Apple and was refunded my credit as there is nothing that can be done presently.

This function could be supported in the Swift Package library, but not executable in the App Clip (as of iOS 15.6 beta).