Fix GitHub Copilot chat authentication on Windows (#15587)
Ramkumar
created
This PR fixes Copilot chat authentication on Windows. GitHub Copilot
chat in assistant panel uses auth token file generated by [copilot
language server](https://github.com/zed-industries/copilot). The path to
authentication token file is platform dependent. On Windows, it happens
to be `~\AppData\Local\github-copilot\hosts.json`.
Release Notes:
- Fixed Copilot chat sign in issue on Windows ([#4673](https://github.com/zed-industries/zed/issues/4673))