Allow Http requests to be recorded without requests being faked

[kemp]

This is a simple PR which allows users to call Http::record(). record has already existed in the framework and is used for faking requests, but I believe it may be useful for testing without also faking the requests.

Usage:

use Illuminate\Support\Facades\Http;

Http::record();

Http::get('https://example.com');

Http::recorded(function (\Illuminate\Http\Client\Request $request, \Illuminate\Http\Client\Response $response) {
    // Do something with the request, response pair
});