XWiki provides no warning when granting XWiki.Notifications.Code.NotificationEmailRendererClass admin right

XWiki is a generic wiki platform. When a user without script right creates a document with an `XWiki.Notifications.Code.NotificationEmailRendererClass` object, and later an admin edits and saves that document, the email templates in this object will be used for notifications. No malicious code can be executed, though, as while these templates allow Velocity code, the existing generic analyzer already warns admins before editing Velocity code. The main impact would thus be to send spam, e.g., with phishing links to other users or to hide notifications about other attacks. 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. This has been patched in XWiki 16.10.2, 16.4.7 and 15.10.16 by adding an analysis for the respective XClass properties.