Webhook logging

[FKlintebackPure]

I could not get my webhooks working, and troubleshooting was tricky since Wiremock not checks for error responses.

A simple warning log would be helpful.

Alternatively, all webhook calls and responses could be logged and retrievable via the admin api.

Suggested code (in WireMockMiddleware.SendToWebHooksAsync):

var result = await webhookSender.SendAsync(httpClientForWebhook, mapping, webhookRequest, request, response).ConfigureAwait(false);
if (result.IsSuccessStatusCode) return;
_options.Logger.Warn($"Sending message to Webhook [{webHookIndex}] from Mapping '{mapping.Guid}' failed. Response: {result}");

[StefH]

@FKlintebackPure
This will be added in next release.

#946