Added The command-line flags --doh-routes, --doh-insecure-enabled. proxy.HTTPConfig and proxy.Config.HTTPConfig. Removed proxy.BeforeRequestHandler, proxy.BeforeRequestError, and proxy.Config.BeforeRequestHandler. Use proxy.Middleware interface instead. proxy.Config.HTTPSServerName, proxy.Config.HTTPSListenAddr, proxy.Config.HTTP3, and proxy.Config.UserInfo.