feat(service): proxy setting

[UsherFall]

Services like discord, telegram are not available directly in my country, so proxy setup is required for me.

In telegram, I can use SetClient to set proxy, but how can I set proxy for discord or other service

client, err := api.NewBotAPIWithClient(apiToken, proxy.ProxyHttpClient)
if err != nil {
	return nil, err
}
t := &telegram.Telegram{}
t.SetClient(client)