Added support for future insertion of the ArchiveRequest's objectstore

continuousintegration/orchestration/tests/prepare_tests.sh

scheduler/OStoreDB/OStoreDB.cpp

scheduler/OStoreDB/OStoreDB.hpp

scheduler/OStoreDB/OStoreDBFactory.hpp

scheduler/Scheduler.cpp

scheduler/Scheduler.hpp

scheduler/SchedulerDatabase.hpp

xroot_plugins/XrdSsiCtaRequestMessage.cpp