[composer-based] Bond RedirectToRouteRector to symfony/framework-bundle 2.6

[TomasVotruba]

Reopens #990 without the dependency change. composer.json is untouched here.

RedirectToRouteRector rewrites the redirect helper pair into the shorter route helper:

 final class SomeController extends AbstractController
 {
     public function someAction()
     {
-        return $this->redirect($this->generateUrl('something', ['id' => $id]));
+        return $this->redirectToRoute('something', ['id' => $id]);
     }
 }

Controller::redirectToRoute() was added in symfony/framework-bundle 2.6, so the rule declares that package constraint and joins the composer-based set:

public function provideComposerPackageConstraint(): ComposerPackageConstraint
{
    return new ComposerPackageConstraint('symfony/framework-bundle', '>=2.6');
}

A project on an older framework-bundle now gets the rule skipped instead of a call to a method that does not exist yet.

Testing a rule bonded to a package we cannot install

ComposerPackageConstraintFilter resolves the constraint against the installed packages, and RectorNodeTraverser applies it unconditionally — including during the rule's own test run. symfony/framework-bundle is not installed here, so the rule was filtered out and all 5 fixtures failed.

Adding it to require-dev is not an option: it does not resolve at any major against the current constraints. ^8.1 conflicts with symfony/console < 8.1 while rector/rector-src pins symfony/console ^6.4.24; ^7.4 needs dependency-injection/routing at ^7.4, currently ^6.4; ^6.4 needs http-kernel ^6.4 and config ^6.1|^7.0, currently ^7.4 and ^8.1.

rectorphp/rector-src#8264 added a hook for exactly this, and the test points at a standalone composer.json:

protected function provideComposerJsonFilePath(): string
{
    return __DIR__ . '/config/composer.json';
}

{
    "require": {
        "symfony/framework-bundle": "^2.6"
    }
}

That hook is merged, so the suite is green on the current rector/rector-src dev-main — 584 tests, including the 7 RedirectToRouteRector cases. ECS, PHPStan, class-leak, Finalize Classes and Composer Validate pass as well.