Authenticate gh cli automatically in integrated terminal

This is a duplicate of https://github.com/cli/cli/issues/1074. I'm creating it here since the implementation should probably belong here.

The gh cli now supports the environment variable GITHUB_TOKEN for authentication. This extension could expose the GITHUB_TOKEN to the integrated terminal in order to automatically provide authentication for gh cli.

Original text:

VSCode now provides GitHub authentication for git even in its Terminal.

If gh had support for that too, we could have a seamless GitHub Authentication when using gh inside VSCode, which can mainly benefit vscode-dev-containers , Visual Studio Codespaces, and therefore, the upcoming GitHub Codespaces.

首先阅读链接的重复 issue #1074 以及所引用的 VS Code GitHub 身份验证更新。检查此扩展如何与集成终端集成；当在那里提供 GITHUB_TOKEN，使 gh 能够自动进行身份验证时，即表示完成。