Add a client variation for Combine

[Felipe Marino]

Description

Create and provide an HTTPClient variation for Combine.
It should be a wrapper over Foundation and it's Combine's conveniences, that will have a more Promise like API than current HTTPClient.
All support types, error, response, etc should be reused as much as possible. The reusable content can be packaged into a HTTPClientCore module, to facilitate breaking HTTPClient into two libraries each one containing each HTTPClient previously mentioned here.

Tasks

• Create and test CombineHTTPClient
• Extract reusable code into HTTPClientCore
• Break HTTPClient into two products