minor #25040 [Form] Add phpdoc to `RequestHandlerInterface::isFileUpload()` method (issei-m)

This PR was squashed before being merged into the 2.7 branch (closes #25040).

Discussion
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[Form] Add phpdoc to `RequestHandlerInterface::isFileUpload()` method

| Q             | A
| ------------- | ---
| Branch?       | 2.7
| Bug fix?      | no
| New feature?  | no <!-- don't forget to update src/**/CHANGELOG.md files -->
| BC breaks?    | no
| Deprecations? | no <!-- don't forget to update UPGRADE-*.md files -->
| Tests pass?   | Not confirmed, but the changes are completely minor
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

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Commits
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faf5470 [Form] Add phpdoc to `RequestHandlerInterface::isFileUpload()` method

src/Symfony/Component/Form/Extension/HttpFoundation/HttpFoundationRequestHandler.php

@@ -108,6 +108,9 @@ class HttpFoundationRequestHandler implements RequestHandlerInterface
         $form->submit($data, 'PATCH' !== $method);
     }
 
+    /**
+     * {@inheritdoc}
+     */
     public function isFileUpload($data)
     {
         return $data instanceof File;

src/Symfony/Component/Form/NativeRequestHandler.php

@@ -118,6 +118,9 @@ class NativeRequestHandler implements RequestHandlerInterface
         $form->submit($data, 'PATCH' !== $method);
     }
 
+    /**
+     * {@inheritdoc}
+     */
     public function isFileUpload($data)
     {
         // POST data will always be strings or arrays of strings. Thus, we can be sure

src/Symfony/Component/Form/RequestHandlerInterface.php

@@ -27,7 +27,9 @@ interface RequestHandlerInterface
     public function handleRequest(FormInterface $form, $request = null);
 
     /**
-     * @param mixed $data
+     * Returns true if the given data is a file upload.
+     *
+     * @param mixed $data The form field data
      *
      * @return bool
      */