Failure to retrieve userinfo is not logged

When the userinfo request fails there is no evidence in of this in the debug logs.
The only indication was that "OIDC user info response" is missing after "OIDC user info request" log message.

This occurs for example if the xwiki server ist not allowed outgoing requests.

Pull request: Log failure of OIDC user info request by ndecker · Pull Request #16 · xwiki-contrib/oidc (github.com)