Automatically log in if my token is expired

[bartTC]

Right now, if your auth token is expired, you learn that via a message. I don't need the extra step, I don't see why you won't want to login at this point.

So this:

❯ apppack config list -a sampleapp
⚠ unable to refresh auth token {"error":"invalid_grant","error_description":"Unknown or invalid refresh token."}
ℹ Reauthenticate this device by running: apppack auth login

❯ apppack auth login
Your verification code is MRJL-VJLX
Finish authentication in your web browser...
✔ Logged in as martin@example.com

Should become:

❯ apppack config list -a sampleapp
⚠ unable to refresh auth token {"error":"invalid_grant","error_description":"Unknown or invalid refresh token."}

ℹ Reauthenticate this required. Please login in your webbrowser.
Your verification code is MRJL-VJLX
Finish authentication in your web browser...
✔ Logged in as martin@example.com

[ipmb]

My only concern with this is if people are using the CLI as part of an automated/unattended script. I'm curious if we can use https://github.com/mattn/go-isatty (which is already a dependency) to detect this.