XWIKI-9071: User E-Mail can be leaked using the "Forgot Password" feature
* Display the password property in the reset password message instead of the raw property value.
* Add a default custom displayer for Email XClass property types that obfuscates the email address.
* Change the type of the email property of XWiki.XWikiUsers class (holding the user profile) from String to Email and remove the custom displayer.