Woah!  Got carried away with const.  This commit Removes the const
qualifier from the ArchiveFileItor::next() method because next()
modifies the iterator.

To loop through an ArchiveFileItor:

  auto itor = catalogue.getArchiveFilesForRepackItor(vid, startFSeq);
  while(itor.hasMore()) {
    const auto archiveFile = itor.next();
    // Do something with archiveFile
  }

Conflicts:
	objectstore/Agent.cpp
	objectstore/RetrieveQueueFailedAlgorithms.cpp
	objectstore/RetrieveQueueToReportAlgorithms.cpp
	objectstore/RetrieveRequest.cpp
	scheduler/OStoreDB/OStoreDB.cpp
	scheduler/OStoreDB/OStoreDB.hpp
	scheduler/OStoreDB/OStoreDBFactory.hpp
	scheduler/OStoreDB/QueueItor.cpp
	scheduler/RetrieveMount.cpp
	scheduler/Scheduler.cpp
	scheduler/SchedulerDatabase.hpp
	xroot_plugins/XrdCtaArchiveFileLs.hpp
	xroot_plugins/XrdCtaListPendingQueue.hpp
	xroot_plugins/XrdCtaTapePoolLs.hpp

It was using vid as container identifier where it should have used
tapepool.

Changed 'catch (cta::exception::Exception ex)' to 'catch (cta::exception::Exception &ex)' in order to avoid error: catching polymorphic type ‘class cta::exception::Exception’

Changed 'catch (cta::exception::Exception ex)' to 'catch (cta::exception::Exception &ex)' in order to avoid error: catching polymorphic type ‘class cta::exception::Exception’ by value

Changed 'catch (exception::Exception ex)' to 'catch (exception::Exception &ex)' in order to avoid error: catching polymorphic type ‘class cta::exception::Exception’ by value

Changed 'catch (std::out_of_range)' to 'catch (std::out_of_range&)' in order to avoid the error: catching polymorphic type ‘class std::out_of_range’ by value

dedicated PV for quarkdb

Previously these were references, but sometimes we want only an archive
queue itor or only a retrieve queue itor. Now we can set the unused
itors to nullptr.

tests and compatible with CI.

Modified MysqlCatalogue.cpp to use autocommitMode default of Stmt::executeQuery() and Stmt::executeNonQuery()

Please note that neither setAutcommitMode() and getAutcommitMode()
should be called for now.  This commit is preparing the future
interface of the code.

Modified RdbmsArchiveFileItorImpl.cpp to use autocommitMode default of Stmt::executeQuery() and Stmt::executeNonQuery()

Modified DropSchemaCmd to use autocommitMode default of Stmt::executeQuery() and Stmt::executeNonQuery()

Modified CreateSchemaCmd to use autocommitMode default of Stmt::executeQuery() and Stmt::executeNonQuery()

Modified RdbmsCatalogue to use autocommitMode default of Stmt::executeQuery() and Stmt::executeNonQuery()

Please note that OracleCatalogue::filesWrittenToTape() now updates the TAPE
table row with AUTOCOMMIT_ON before going on to handle the individual file
entries.  This can be improved when Conn:setAutocommit() becomes available.