CVE-2025-49587: XWiki does not require right warnings for notification displayer objects

When a user without script right creates a document with an XWiki.Notifications.Code.NotificationDisplayerClass object, and later an admin edits and saves that document, the possibly malicious content of that object is output as raw HTML, allowing XSS attacks. While the notification displayer executes Velocity, the existing generic analyzer already warns admins before editing Velocity code. Note that warnings before editing documents with dangerous properties have only been introduced in XWiki 15.9, before that version, this was a known issue and the advice was simply to be careful.