Specify HTTP verb/method for destination monitor

Improvement

Happy to announce that we now have support to select the HTTP verb/method in the destination monitor. 

We use HEAD requests for our destination monitoring tool. As some providers might be blocking HEAD requests, we added the ability to specify the HTTP verb. We've added POST/PATCH/PUT support as well.

When a destination returns a 405 status code ('Method not allowed'), we automatically switch to GET requests.

Specify HTTP verb/method for destination monitor