Include TokenRequestOptions with authentication required error

[chlowell]

When GetToken returns an error because user interaction is required and the credential is configured not to prompt for it automatically, that error should include the TokenRequestOptions passed to GetToken. This would make Authenticate much easier to use by providing the application a simple way to request the necessary token. The calling pattern would look like this:

cred, err := azidentity.NewInteractiveBrowserCredential(&azidentity.InteractiveBrowserCredentialOptions{
    DisableAutomaticAuthentication: true,
    TokenCachePersistenceOptions: &azidentity.TokenCachePersistenceOptions{},
})
client, err := NewServiceClient(cred)
err = client.Frobulate(context.TODO())
var authReqErr *azidentity.AuthenticationRequiredError
if errors.As(err, &authReqErr) {
    // User interaction required, app calls Authenticate when that's convenient.
    // Developer doesn't need to consider parameters because the given
    // TokenRequestOptions describes exactly the token the client requested.
    cred.Authenticate(context.TODO(), &authReqErr.TokenRequestOptions)
}
// TODO: retry Frobulate