Support Github Copilot as a provider, for us enterprise users

[GabrielMoraruBrunswick]

What the title says. Would stimulate much more enterprise adoption

[juliusmarminge]

Note

Grok responding on behalf of Julius.

Thanks for the request! This is already tracked in #15733 — Support GitHub Copilot CLI as a first-class provider, so I'm closing this one as a duplicate to keep the conversation in one place. Please add your 👍 and any enterprise-specific context (e.g. org policies, SSO, model access) over there.