[config] Avoid relying on shared_dir method when possible From 3.26, some "data" directories (like web/data and i18n or wdoc) are installed along with CubicWeb in site packages. So we can retrieve them relatively to the module that needs them (namely "cubicweb" for "i18n" and "cubicweb.web" for "web/data" and "wdoc"). Reason for doing this is that "share_dir()" is not working when cubicweb is installed in "develop" mode and we are about to drop this method. Related to #17132990.