Allow pagination for retrieval of process instances via KogitoApp REST API

When a user has just KogitoApp deployed with persistence (Infinispan) then there is no other way of retrieving process instances from Kogito Service than querying them all at once. This is sufficient for smaller amounts of process instances. But in case a lot of instances is running on the service, it can take a lot of time to get them all and this results usually in 504 Gateway Timeout. It would be good to have pagination for that as there may be scenarios when Data Index is not needed/used but processes have to be queried either all at once or we can query one process instance if we know its process instance ID.

The other option would be to at least return just IDs (keys in Infinispan) as this should considerably reduce the amount of processing needed because there won't be any unmarshalling of process instances from Protobuf to Java classes taking place.