Rethink configuration to make a lot easier to define own handlers

[hrach]

https://github.com/nextras/migrations/commit/d46cbd649df0def60e5630e9943fba3ab432ed93#commitcomment-24528344

[hrach]

Current sad sollution:

extensions:
    nextras.migrations: Nextras\Migrations\Bridges\NetteDI\MigrationsExtension

services:
    nextras.migrations.configuration:
        factory: MigrationConfiguration
        arguments:
            - %appDir%/../migrations
            - @Nextras\Migrations\IDriver
            - false
            - []
            - @Nette\DI\Container

nextras.migrations:
    dir: %appDir%/../migrations
    driver: pgsql
    dbal: nextras

<?php declare(strict_types = 1);

use Nette\DI\Container;
use Nextras\Migrations\Configurations\DefaultConfiguration;
use Nextras\Migrations\IDriver;

class MigrationConfiguration extends DefaultConfiguration
{
    /** @var Container */
    private $container;

    public function __construct($dir, IDriver $driver, $withDummyData = true, array $phpParams = [], Container $container)
    {
        parent::__construct($dir, $driver, $withDummyData, $phpParams);
        $this->container = $container;
    }

    public function getExtensionHandlers()
    {
        $handlers = parent::getExtensionHandlers();
        $handlers['php'] = $this->container->getByType(ConnectionPhpHandler::class);
        return $handlers;
    }
}