Client plugins API

[rsinukov]

[e5l]

I played a lot and it is great.

There are 2 points I found:

• I missed the simple way of creating HttpClientCall and HttpResponse from HttpRequestBuilder without making a network call.

• I would also replace HttpClientCall with HttpResponse in the public API.

[rsinukov]

@e5l Nice! Can you add these points to the design ticket please, so that we have discussion in one place?

[e5l]

@rsinukov Sure. Done!