Merge branch '6.3' into 6.4

* 6.3:
  [Validator] Add annotation in Constraint
  [VarExporter] Remove unused test files
  [FrameworkBundle] Remove unused test file
  [DependencyInjection] Remove unused test file
  [HttpKernel] Fix missing Request in RequestStack for StreamedResponse
  Psalm: Ignore UnusedClass errors
  fix(console): avoid multiple new line when message already ends with a new line

Author: nicolas-grekas

StreamedResponse.php

@@ -56,6 +56,11 @@ public function setCallback(callable $callback): static
         return $this;
     }
 
+    public function getCallback(): \Closure
+    {
+        return ($this->callback)(...);
+    }
+
     /**
      * This method only sends the headers once.
      *