Support proxy authentication
Summary
In case of the HTTP status code 407 - Proxy Authentication Required we should gracefully handle the error.
Logs
GitLab Workflow
2024-01-31T11:06:22:798 [info]: Configuring Language Server - baseUrl: https://gitlab.com
2024-01-31T11:06:22:800 [debug]: Using non-expired account https://gitlab.com|xxxx.
2024-01-31T11:06:22:879 [warning]: Token validation failed in Language Server: (Failed to check token: Error: authenticationrequired - unknown). This can happen with OAuth token refresh. If the rest of the extension works, this won't be a problem.
GitLab Language Server
2024-01-31T11:06:22:811 [info]: Checking token for OAuth validity
2024-01-31T11:06:22:811 [debug]: fetch: request for https://gitlab.com/oauth/token/info made with proxy agent.
2024-01-31T11:06:22:877 [debug]: fetch: request to https://gitlab.com/oauth/token/info returned HTTP 407 after 66 ms
2024-01-31T11:06:22:877 [error]: Error performing token check
Edited by Erran Carey