Respect the SSO challenge as received from the API when using a PAT #5002
Description
When a Personal Access Token is used with GitHub CLI for authentication, the token might not be authorized to resources in a specific organization. In that case, the API will present a challenge via response headers:
X-GitHub-SSO: required; url=<URL>
GitHub CLI should parse this response header and present an option to the user to follow the authorization URL in their browser.
Followup to #4241
Re: SAML enforcement