Add support for dblist properties using a custom query in the link refactoring

XWIKI-19219 adds support for database list properties in the link refactoring: the pages stored in such a property are listed as backlinks of the target page and are updated when that page is renamed or moved.

This only works for database lists whose values are known to be page references, i.e. when no custom query is used and the generated query selects doc.fullName as the stored value (only a class name, or doc.fullName as id or value field). A database list configured with a custom query is ignored, even when that query selects page references, so renaming a page leaves such a property pointing to the old page.

See the discussion in https://github.com/xwiki/xwiki-platform/pull/6509#discussion_r4123416003