Add a new URL path scheme that allows to specify the wiki id for any action

It is currently not possible to build for an XWiki instance an URL that would be correct for any subwiki without getting from the wiki descriptor the URL scheme for this subwiki.
So it would be useful to have a dedicated URL scheme that we could use to build such URLs without having to know if the wiki is configured to be used with path-based or domain-based URL and which would redirect to the right domain in case of latter configuration.

So I propose that we use the following scheme for such URLs:
http://domain/xwiki/wiki-id/[ID of the wiki]/action/space/page

So basically a scheme very close to the path-based scheme except on the usage of wiki-id instead of wiki.