New config.factory.lazy service allows services to lazily load config storage

Services can now depend on a new config.factory.lazy service, a drop-in replacement for config.factory which lazily loads the config.factory service if/when it is actually needed. This works around a circular reference that appeared if a config storage dependency (such as an alternative cache backend) required logging, and a logger depended on config storage.

The \Drupal\syslog\Logger\SysLog service now depends on config.factory.lazy rather than config.factory.