Investigate and Rework Multiple Cache Loaders Support

Today having more than one loader configured is possible. However the way it operates is not well defined or even documented.

Currently for single key operations we try each loader one by one until one returns non null. For writes we write to all stores. However for bulk operations we only load from the first AdvancedLoader. This can be a bit confusing how these are done, but makes sense at least when thought about.

The other concern that is new is now that we have segmented loaders that perform better under bulk operations that their non segmented counterparts. ISPN-9816 makes it better, however its checking is not the most foolproof. We may want to instead explicitly find per invocation if the current loader is segmented or not before invoking the appropriate method. Currently we only check at startup if any loader is segmented; however this can be problematic if the first loader is not segmented and not advanced or handle the case of a loader being removed at runtime.