[media] bug fix - string to int (#9156)

Fix error:

```
PHP Fatal error: Uncaught TypeError: LORIS\media\MediaFile::getHideFile(): Return value must be of type int, string returned in /var/www/Loris/modules/media/php/mediafile.class.inc:85\nStack trace:\n#0 /var/www/Loris/modules/media/php/hidefilefilter.class.inc(50): LORIS\media\MediaFile->getHideFile()\n#1 /var/www/Loris/src/Data/
```

modules/media/php/mediafile.class.inc

@@ -82,6 +82,9 @@ class MediaFile implements \LORIS\Data\DataInstance,
      */
     public function getHideFile(): int
     {
-        return $this->DBRow['hideFile'];
+        if ($this->DBRow['hideFile'] == 'hidden') {
+            return 1;
+        }
+        return 0;
     }
 }