Add support for connection.update-secret

[Zerpet]

This method is in the AMQP 0.9.1 spec and it is supported by RabbitMQ.
This is useful when the secret used in the connection has an expiry, as
it allows the applications to renew the secret without the hassle of
closing-reconnecting consumers/producers.

[Gsantomaggio]

Looks to me.
I tested it with https://github.com/rabbitmq/rabbitmq-oauth2-tutorial

package main

import (
	"context"
	"encoding/json"
	"fmt"
	amqp "github.com/rabbitmq/amqp091-go"
	"io/ioutil"
	"net/http"
	"strings"
	"time"
)

func main() {
	fmt.Println(GetToken())

	connection, err := amqp.DialConfig(fmt.Sprintf(
		"%s://%s:%s@%s:%s/%s",
		"amqp",
		"",
		GetToken(),
		"localhost",
		"5672",
		"/",
	), amqp.Config{})

	if err != nil {
		panic(err)
	}
	channel, err := connection.Channel()
	if err != nil {
		panic(err)
	}
	for i := 0; i < 1000; i++ {

		err := channel.PublishWithContext(context.Background(), "", "test-key", false, false, amqp.Publishing{})
		if err != nil {
			fmt.Printf("Error %s\n", err)
			return
		}

		if i%59 == 0 {
			err := connection.UpdateSecret(GetToken(), "test-key")
			fmt.Printf("Update secret\n")
			if err != nil {
				fmt.Printf("UpdateSecret Error %s\n", err)

				return
			}
		}

		time.Sleep(1 * time.Second)
		fmt.Printf("Sent %d\n", i)
	}
	defer connection.Close()

}

type Access struct {
	AccessToken string `json:"access_token"`
}

func GetToken() string {
	url := "http://localhost:8080/realms/test/protocol/openid-connect/token"
	method := "POST"

	payload := strings.NewReader("client_id=producer&client_secret=kbOFBXI9tANgKUq8vXHLhT6YhbivgXxn&grant_type=client_credentials")

	client := &http.Client{}
	req, err := http.NewRequest(method, url, payload)

	if err != nil {
		fmt.Println(err)
		return ""
	}
	req.Header.Add("Content-Type", "application/x-www-form-urlencoded")

	res, err := client.Do(req)
	if err != nil {
		fmt.Println(err)
		return ""
	}
	defer res.Body.Close()

	body, err := ioutil.ReadAll(res.Body)
	if err != nil {
		fmt.Println(err)
		return ""
	}

	var x = Access{}
	err = json.Unmarshal(body, &x)
	if err != nil {
		return err.Error()
	}
	return x.AccessToken
}