Possible browser cache issue with SSX/JSX when testing two different version of XWiki on the same server

Since XWIKI-12981 document based SSX and JSX add the document version to the URL which means if the result of the JSX does changes without changing the document version you end up with the wrong version.

The typical use case is testing several versions of XWiki without going trough an upgrade.

Currently AbstractDocumentSkinExtensionPlugin#getDocumentSkinExtensionURL adds the document version as a query string. We should probably consider adding (or replace with) another criteria like the document date.