Make our datumctl oauth dialog work outside of the local machine #507
Description
When you call datumctl auth login, you need to visit a URL like this in a browser:
https://auth.datum.net/oauth/v2/authorize?client_id=SECRET&code_challenge=UhXCJ7Qmd1zjUuzouHY70ex2jIgtuCLe02edVmeB-Hs&code_challenge_method=S256&redirect_uri=http%3A%2F%2F127.0.0.1%3A35169%2Fdatumctl%2Fauth%2Fcallback&response_type=code&scope=openid+profile+email+offline_access&state=wc8QI6VTJMQfOyI6SbQ9HGBeFrbIjRIai7J4od_O4WY
The http%3A%2F%2F127.0.0.1%3A35169 in there is problematic because if you're on a remote machine or VM there isn't a localhost service to call back too. You'd either have to use a remote browser, or tunnel localhost back to the VM. Though the second option will be much easier when we get our tunnels operational, we should look at how much effort is involved in generating a code that can be pasted back into the terminal, the same way that GitHub, gcloud, and other CLIs work.