minor #47370 Remove usage of empty function when possible (alamirault)

This PR was squashed before being merged into the 6.2 branch.

Discussion
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Remove usage of empty function when possible

| Q             | A
| ------------- | ---
| Branch?       | 6.2
| Bug fix?      | no
| New feature?  | no <!-- please update src/**/CHANGELOG.md files -->
| Deprecations? | no <!-- please update UPGRADE-*.md and src/**/CHANGELOG.md files -->
| Tickets       | Fix #... <!-- prefix each issue number with "Fix #", no need to create an issue if none exist, explain below instead -->
| License       | MIT
| Doc PR        | symfony/symfony-docs#... <!-- required for new features -->

In recent code reviews we suggest to use `!$var` instead of `empty($var)`

In order to keep same code style in codebase, I replaced usages of empty when it is possible and typehinted

Commits
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026edbe601 Remove usage of empty function when possible

Author: fabpot

EventListener/AbstractSessionListener.php

@@ -151,7 +151,7 @@ public function onKernelResponse(ResponseEvent $event)
                 $request = $event->getRequest();
                 $requestSessionCookieId = $request->cookies->get($sessionName);
 
-                $isSessionEmpty = ($session instanceof Session ? $session->isEmpty() : empty($session->all())) && empty($_SESSION); // checking $_SESSION to keep compatibility with native sessions
+                $isSessionEmpty = ($session instanceof Session ? $session->isEmpty() : !$session->all()) && empty($_SESSION); // checking $_SESSION to keep compatibility with native sessions
                 if ($requestSessionCookieId && $isSessionEmpty) {
                     // PHP internally sets the session cookie value to "deleted" when setcookie() is called with empty string $value argument
                     // which happens in \Symfony\Component\HttpFoundation\Session\Storage\Handler\AbstractSessionHandler::destroy