Refactor the CloneableRequestMessage

[nozzlegear]

I want to rework the whole concept of the CloneableRequestMessage. Rather than cloning the request message, we'll use a sort of HttpMessage object that has configuration data about the request but is not disposable and does not do the request itself. It's simply used to create the request. It will hold the data being sent to Shopify, along with the Http method used, the url, headers, and so on.

Related: #1001