loopy unpacking and multi packing

Current implementation of persistency configures a packer and unpacker for each location. This MR changes this to:

• one packer per object type
• each unpacker for a given location also unpacks all linked locations if they are not unpacked already. This will allow to request a location to be unpacked individually.
• Packing and unpacking configurations are simplified. PersistRecoConf is removed as most of it's functionality is not needed anymore.

Part of set !3750 (merged) DaVinci!747 (merged) MooreAnalysis!92 (merged) Analysis!918 (merged) Moore!1638 (merged)

Event/EventPacker/src/component/BufferRelationUnpackerBaseAlg.h

@@ -64,15 +64,20 @@ namespace DataPacking::Buffer {
 
       const Gaudi::StringKey PackedObjectLocations{"PackedObjectLocations"};
 
-      auto* rels = m_rels.put( std::make_unique<RELATION>() );
-
       const auto& s2i = m_annsvc->s2i( buffers.key(), PackedObjectLocations );
       auto        j   = s2i.find( m_rels.fullKey().key() );
       if ( j == s2i.end() ) {
-        throw GaudiException{"Could not find entry for requested output", __PRETTY_FUNCTION__, StatusCode::FAILURE};
+        ++m_unknown;
+        return;
       }
+
+      auto* rels = m_rels.put( std::make_unique<RELATION>() );
       const auto* buffer = buffers.find( j->second );
-      if ( !buffer || !buffer->buffer().size() ) return;
+      if ( !buffer ) {
+          ++m_absent;
+          return;
+      }
+      if (buffer->buffer().size()==0) return;
 
       Buffer readBuffer{*buffer}; // TODO: avoid copying just because 'pos' gets updated -- allow a 'shallow' emphemeral
                                   // version which allows reading
@@ -274,8 +279,9 @@ namespace DataPacking::Buffer {
 
     DataObjectWriteHandle<RELATION> m_rels{this, "OutputName", ""};
 
+    mutable Gaudi::Accumulators::MsgCounter<MSG::ERROR> m_unknown{this, "Requested output is not known for the given input stream - not creating output"};
+    mutable Gaudi::Accumulators::MsgCounter<MSG::WARNING> m_absent{this, "Requested output is known, but not present in packed data - creating empty container"};
     mutable Gaudi::Accumulators::StatCounter<> m_unpackedData{this, "# PackedData"};
-
     mutable Gaudi::Accumulators::StatCounter<> m_missingLinks{this, "# Missing Link Locations"};
   };