Some attribute not escaped in Validate::isCleanHTML method

PrestaShop is an open-source e-commerce platform. Prior to versions 8.1.3 and 1.7.8.11, some event attributes are not detected by the `isCleanHTML` method. Some modules using the `isCleanHTML` method could be vulnerable to cross-site scripting. Versions 8.1.3 and 1.7.8.11 contain a patch for this issue. The best workaround is to use the `HTMLPurifier` library to sanitize html input coming from users. The library is already available as a dependency in the PrestaShop project. Beware though that in legacy object models, fields of `HTML` type will call `isCleanHTML`.