Extend Marshaller interface to expose configured ClassWhiteList to implementation

ClassWhiteList is a generic white list that can be configured via our XML, it doesn't have anything specifc to Serialization. We should allow a user's marshaller implementation, set via SerializationConfiguration#marshaller, to utilise the configured values to limit what can/can't be marshalled.

For our internal code this is nice because it will prevent us from requiring hacky code like the following in the PersistenceMarshallerImpl if the user wants to utilise our provided JavaSerializationMarshaller:

if (userMarshaller instanceof JavaSerializationMarshaller) {
   ((JavaSerialzationMarshaller) userMarshaller).setWhiteList(whiteListImpl);
} else if (userMarshaller instanceof ...) {
   ...
}

Proposed change to the Marshaller interface:

default void initialize(ClassWhiteList whiteList) {
   // no-op
}