Added a new method to generate parameters.yml automatically

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | https://github.com/symfony/symfony-standard/issues/691
| License       | MIT
| Doc PR        | -

This is the first step into removing the parameter handler when installing Symfony.
Maybe we should write a message? Something like this (I'm taking shor

```php
$event->getIO()->write(sprintf(
    'The configuration %s was just created for you. You can modify this to fit your system settings.',
    $appDir.'/config/parameters.yml'
));
```