add coroutine support

[kpicaza]

Description

Add coroutine support to allow running async code in a sync flow:

Pros

• It allows using promises like synchronous code.

Cons

• Consumes more memory than promises
• Is a little slower than promises

Example:

PSR-7 Request Handler

Promise Based

<?php
declare(strict_types = 1);

namespace App;

use Antidot\React\PromiseResponse;
use Psr\Http\Message\ResponseInterface;
use Psr\Http\Message\ServerRequestInterface;
use Psr\Http\Server\RequestHandlerInterface;
use function React\Promise\resolve;

class SomeRequestHandler implements RequestHandlerInterface
{
    public function handle(ServerRequestInterface $request): ResponseInterface
    {
        return new PromiseResponse(resolve($request)->then(
            function(ServerRequestInterface $request): ResponseInterface {
                return new Response('Hello World!!!');
            }
        ));
    }
}

Coroutine based

<?php
declare(strict_types = 1);

namespace App;

use Antidot\React\PromiseResponse;
use Psr\Http\Message\ResponseInterface;
use Psr\Http\Message\ServerRequestInterface;
use Psr\Http\Server\RequestHandlerInterface;
use function React\Promise\resolve;

class SomeRequestHandler implements RequestHandlerInterface
{
    public function handle(ServerRequestInterface $request): ResponseInterface
    {
        return PromiseResponse::fromGeneratorCallback(
            function(ServerRequestInterface $request): \Generator {
                $message = yield resolve('Hello World!!!');
            
                return new Response($message);
            }
        ));
    }
}