Issue reporter fails to run duplicate search

[chrmarti]

The console shows:

Access to fetch at 'https://vscode-probot.westus.cloudapp.azure.com:7890/duplicate_candidates' from origin 'vscode-file://vscode-app' has been blocked by CORS policy: Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource. If an opaque response serves your needs, set the request's mode to 'no-cors' to fetch the resource with CORS disabled.

[bpasero]

@RMacfarlane you will need to enable CORS for that endpoint for the origin: Access-Control-Allow-Origin: vscode-file://vscode-app

See https://github.com/microsoft/vscode-internalbacklog/issues/1824 for more info.