cli: don't error if source id doesn't exist

[jmorganca]

Fixes #408

[mxyng]

As mentioned offline, need to be careful with this since the same code path is used by infra tokens create to if the user session is timed out. Since that's generally invoked by kubectl, the non-interactiveness would cause the command line to be blocked indefinitely. Could try changing to Interactive client but that's a larger change.

For the time being, it might be sufficient to use the source domain as the selector instead of ID.

[jmorganca]

As of the latest change:

• Added the constraint that we won't support non-interactive logins (yet) Support non-interactive login #488 . This should remove the need for a lock (and potential blocking) since all auth flows should be in the user's foreground/terminal now.
• kubectl will now correctly prompt users for data if needed at login. Usually, users won't need this, but worst case it works great as well now (survey can print to stderr)

Follow up changes that I've left out to keep this PR small:

• Render ANSI colors correctly on Windows and when output from kubectl #399
• Host flag #495
• Prompt user for registry host when running infra login #496

[mxyng]

What's the definition of non-interactive in this context?

[mxyng]

This means to me adding support for command line parameters to fill in the fields we would other prompt user. Not sure if it will address the issues with desktop apps needing to reauth

[jmorganca]

Yep that's correct, more specifically when no TTY is available for stdin. For Desktop apps we should consider refresh tokens or another mechanism that allows for transparently renewing session duration

[mxyng]

Once we have APIs to add sources, this should prompt user to input a source rather than error out