No access to HttpClient for logging requests and responses and for end-to-end-testing

[kareldonk]

I was looking for ways to be able to have access to the HttpClient used by ShopifySharp, to be able:

1. to easily log requests and responses for all HTTP communication and
2. perhaps more importantly to be able to mock the HttpClient so that we could implement E2E-testing.

I saw in the code that there are plans to make this possible. Any idea on when this will be enabled and released?