Feature: use `VerificationURIComplete` from oauth2 response in CLI login prompt if available

### Describe the feature

`DeviceAuthResponse` in oauth2 package provides the `VerificationURIComplete` field which includes the device code in the URI (see [this](https://cs.opensource.google/go/x/oauth2/+/refs/tags/v0.35.0:deviceauth.go;l=35)).

We can present this URI to the user while authenticating, allowing them to easily complete the authentication process without needing to manually enter the device code.

### Describe the ideal solution

Use `VerificationURIComplete` if set, fall back to `VerificationURI` otherwise.

Start at the CLI login prompt and trace where the oauth2 DeviceAuthResponse is handled. Use VerificationURIComplete when it is set and VerificationURI otherwise; done means the prompt presents the complete URI when available while retaining the fallback behavior.

Written by the indexing model from the issue text.