XWIKI-8822: Set virtual=1 by default and deprecate the virtual mode API
- Exposing farm related information and buttons in the EM UI
XWIKI-8876: Promote the wiki-manager's XWiki.XWikiServerClass to "mandatory class" status for the main wiki
- Make the ApplicationManager part of XWikiServerClass load the existing class from the database (where it was already initialized by the mandatory document initializer).