Authenticate to git provider using single sigin-on

👋🏼,

Is it possible to authenticate vendir when trying to pull from a git provider in which you have access to via SSO? We can't create passwords as our accounts are managed centrally.

No files, tests, or entry points are identified. First clarify which git provider and SSO mechanism must be supported, then locate vendir's git authentication entry point and existing credential handling. Done means the agreed SSO-based authentication flow works for the target provider and has coverage for the relevant authentication path.

Written by the indexing model from the issue text.