Nicer error messages for migrating users

[sergei1152]

The error message for a user that still had the old auth method but trying to use the new account api was like "please use parallel-cli login" which is confusing since they are already authenticated. Change the error message to detect this case and make it friendlier.

This is the output now:

Authentication required: This operation requires Account API credentials, but your stored credentials only authorize the standard Parallel API. Re-run 'parallel-cli login' to authenticate against the Account API.

For normal users that never had the original cli installed we will show:

Authentication required: not logged in; run 'parallel-cli login'