Support dependency injection for factory functions in Container config

[clue]

This changeset adds support for dependency injection for factory functions in the Container configuration. This allows us to fine-tune the autowiring behavior and explicitly configure individual parameters while relying on autowiring defaults for other parameters. This does not otherwise break existing APIs, so this is a pure feature addition.

<?php

require __DIR__ . '/../vendor/autoload.php';

$container = new FrameworkX\Container([
    Acme\Todo\UserController::class => function (React\Http\Browser $browser) {
        // example UserController class requires two arguments:
        // - first argument will be autowired based on class reference
        // - second argument expects some manual value
        return new Acme\Todo\UserController($browser, 42);
    }
]);

// …

Builds on top of #96