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.

まず、リンクされている重複 issue #1074 と、参照されている VS Code の GitHub 認証更新を読んでください。この拡張機能が統合ターミナルとどのように連携しているかを調査してください。gh が自動的に認証できるよう、そこに GITHUB_TOKEN を公開できれば完了です。