Routing support for non-invokable controllers

[davisenra]

Hello, everyone!

I've been dabbling with the framework for the past few days on my free time at work and I really like the project!
One thing that bothered me while building a small POC project was defining a new invokable class for each one of my endpoints, on large projects I think this is a nice pattern, but for simpler applications I enjoy grouping endpoints on the same controller class, for example: FooController::index, FooController::create, FooController::update, etc, right now this is not possible.

Do you guys think this could be a good feature? The syntax I have in mind is basically what everyone has seen on other PHP frameworks, something like:

$app->get('/', [HelloController::class, 'index']);

The Symfony approach with attributes would be even cooler, but I think that would require a lot more work.

I was able to make the following test pass without messing too much with the code, if it sounds like a good idea I can send a draft PR and we can go on from there. I only had to change RouteHandler::map to check if $handler is an array and also had to touch Container::callable.

public function testHandleRequestWithNonInvokableControllerClass(): void
{
    $controller = new class {
        public function endpoint(): Response
        {
            return new Response(200, [], '');
        }
    };

    $handler = new RouteHandler();
    $handler->map(['GET'], '/', [$controller::class, 'endpoint']);

    $request = new ServerRequest('GET', '/');
    $response = $handler($request);

    $this->assertInstanceOf(Response::class, $response);
}

Let me know what you guys think :)