Use a dedicated Code OSS client id in GitHub Auth

[TylerLeonhardt]

Code OSS (and anything that forks it...) gets VS Code's client id. While this is unpreventable and not a concern from a security perspective, we can at least prevent accidental usage of the VS Code client id by replacing it with a Code OSS dedicated client id.

[TylerLeonhardt]

Reverted #252559 see that for more info.