Add support for multiple configurable webhook URLs

[Goncharo]

Problem

From a cx: "is it possible to have more than one webhook for the sandbox environment? I need to set up one webhook for our staging environment, another one to connect to my localhost through ngrok tunneling. Currently I have to toggle between the two when I do local development."

Suggested solution

Add ability to specify multiple URLs, and have the webhooks always sent to all specified URLs.

Alternatives

No response

Additional context

https://metriport.slack.com/archives/C06T841KMGV/p1713894290310939