chore: add simple validation for static dialer-proxy config (#2551)

Currently, it can only validate whether a cycle exists in proxies, and cannot determine if it is caused by groups.

config/config.go

@@ -955,6 +955,12 @@ func parseProxies(cfg *RawConfig) (proxies map[string]C.Proxy, providersMap map[
 		)
 		proxies["GLOBAL"] = adapter.NewProxy(global)
 	}
+
+	// validate dialer-proxy references
+	if err := validateDialerProxies(proxies); err != nil {
+		return nil, nil, err
+	}
+
 	return proxies, providersMap, nil
 }