XCOMMONS-717: Safe XStreamSerializer implementation serializes component manager referensed from GenericProvider

[misc] No need to deprecate it after all, it's still usefull (even if I would probably not have added it the progress manager component already existed)

* add wrapper

* a few improvements

* add missing @since

* Add a test about <span> element.

XWIKI-7780 : Rating and advice system for extensions

- move the implementation of ratings from the general AbstractExtension to the more specific XWikiExtension

- return the repository from which the rating was fetched

- make the xwiki repository implement Ratable in order to be able to know which repositories support ratings and which do not
- add rating information to the AbstractExtension

- updated the repository schema to include information related to ratings

XCOMMONS-706: Stop storing Maven properties in Extension properties

* remove comment