Update annotations to OpenApi 3

Most of the API annotations are directly converted. The changes in meaning are:
- Parameters "in body" is not supported anymore. These are changed to "in query" or to a request body (depending on the code).

src/Wallabag/ApiBundle/Controller/ConfigRestController.php

@@ -5,7 +5,7 @@ namespace Wallabag\ApiBundle\Controller;
 use JMS\Serializer\SerializationContext;
 use JMS\Serializer\SerializerInterface;
 use Nelmio\ApiDocBundle\Annotation\Operation;
-use Swagger\Annotations as SWG;
+use OpenApi\Annotations as OA;
 use Symfony\Component\HttpFoundation\JsonResponse;
 use Symfony\Component\Routing\Annotation\Route;
 
@@ -17,7 +17,7 @@ class ConfigRestController extends WallabagRestController
      * @Operation(
      *     tags={"Config"},
      *     summary="Retrieve configuration for current user.",
-     *     @SWG\Response(
+     *     @OA\Response(
      *         response="200",
      *         description="Returned when successful"
      *     )