Merge branch '6.4' into 7.1

* 6.4:
  fix: ignore missing directory in isVendor()
  [OptionsResolver] Allow Union/Intersection Types in Resolved Closures
  Issue #58821: [DependencyInjection] Support interfaces in ContainerBuilder::getReflectionClass().
  Dynamically fix compatibility with doctrine/data-fixtures v2
  [HttpKernel] Ensure HttpCache::getTraceKey() does not throw exception
  don't call EntityManager::initializeObject() with scalar values
  [Validator] review italian translations
  Update PR template

Author: nicolas-grekas

ContainerBuilder.php

@@ -353,7 +353,7 @@ public function getReflectionClass(?string $class, bool $throw = true): ?\Reflec
                 $resource = new ClassExistenceResource($class, false);
                 $classReflector = $resource->isFresh(0) ? false : new \ReflectionClass($class);
             } else {
-                $classReflector = class_exists($class) ? new \ReflectionClass($class) : false;
+                $classReflector = class_exists($class) || interface_exists($class, false) ? new \ReflectionClass($class) : false;
             }
         } catch (\ReflectionException $e) {
             if ($throw) {