Align GitHub and GitHub Repositories extension scopes

[TylerLeonhardt]

Because of the alignment we did here:
microsoft/vscode-pull-request-github#3377

GitHub Repos & GHPRI now have the same scopes... unfortunately, the built-in GitHub extension did not receive the same alignment and as a result, you get 2 sign-ins back to back when using GitHub Repos on Desktop:

1. to get the repo picker to load (GH extension)
2. to load the remote workspace (GHR extension)

We should have the GitHub extension request: ['repo', 'workflow', 'user:email', 'read:user'] so that all of our extensions here are aligned.

We need to do this alignment because GitHub doesn't have a mechanism yet for "token downscoping".