Create helper function WriteToHTTPResponse

[CNA-Bld]

This helper function makes it easier to use webhook feature "Making requests when getting updates".

This makes it faster to write simple and stupid bots, especially with serverless deployment. For instance, an inline Markdown bot only needs 15 LOC, without even using a BotAPI instance, and without sending any outgoing HTTP requests:

package main

import (
	"encoding/json"
	"io/ioutil"
	"net/http"

	"github.com/go-telegram-bot-api/telegram-bot-api/v5"
)

func DemoWebhook(w http.ResponseWriter, r *http.Request) {
	bytes, _ := ioutil.ReadAll(r.Body)

	var update tgbotapi.Update
	json.Unmarshal(bytes, &update)

	if update.InlineQuery != nil && update.InlineQuery.Query != "" {
		tgbotapi.WriteToHTTPResponse(w, tgbotapi.InlineConfig{
			InlineQueryID: update.InlineQuery.ID,
			Results: []interface{}{
				tgbotapi.NewInlineQueryResultArticleMarkdown("id", "Markdown", update.InlineQuery.Query),
			},
		})
	}
}

func main() {
	http.HandleFunc("/", DemoWebhook)
	http.ListenAndServe(":8080", nil)
}