Run Rector upgrade script as Composer plugin

[rvanlaak]

Given PHP 8.0 will be the minium PHP version for v2, running a Rector upgrade script will always upgrade the annotations to attributes.

This idea came up during the PHPWVL talk where Tomas Votruba held a talk about including effortless upgradeability as a Composer Plugin, and is a follow-up of the discussion in #72

TODO

• find a way how to hook into the Rector process to transform the parameter labels
• rewrite the old route array values to routeName, routeParameters, routeAbsolute
• find a way to run a Rector rule when installing v2 (and how to only run it once)

Sample Rector rule

return static function (ContainerConfigurator $containerConfigurator): void {
    $services = $containerConfigurator->services();
    $services->set(AnnotationToAttributeRector::class)->call('configure', [
        [
            AnnotationToAttributeRector::ANNOTATION_TO_ATTRIBUTE => ValueObjectInliner::inline([
                new AnnotationToAttribute(\APY\BreadcrumbTrailBundle\Annotation\Breadcrumb::class),
            ]),
        ],
    ]);
};

[rvanlaak]

Created an issue with Rector to ask about modifying parameter labels rectorphp/rector#6825