MarshallableEntryFactory allow lazy marshalling of key/values

Currently it's not possible to create a MarshallableEntry via the MarshallableEntryFactory without eagerly marshalling the key, value and metadata. The intention of this was to ensure that async writes to the cache store fail-fast, opposed to on one of the async threads where the cache put would not fail. However, this also means that when utilising a local embedded jcache instance with the JCacheLoaderAdapter it's necessary for the key/value to be marshalled.

We should create a new method MarshallableEntryFactory#createLazily(Object key, Object value) to allow for lazy marshalling in these circumstances.