Auto: abcip-2.3 — descriptions to OPC UA Description

Threads tag/UDT-member descriptions captured by the L5K (#346) and L5X
(#347) parsers through AbCipTagDefinition + AbCipStructureMember into
DriverAttributeInfo, so the address-space builder sets the OPC UA
Description attribute on each Variable node. L5kMember and L5xParser
also now capture per-member descriptions (via the (Description := "...")
attribute block on L5K and the <Description> child on L5X), and
L5kIngest forwards them. DriverNodeManager surfaces
DriverAttributeInfo.Description as the Variable's Description property.

Description is added as a trailing optional parameter on
DriverAttributeInfo (default null) so every other driver continues
to construct the record unchanged.

Closes #231

src/ZB.MOM.WW.OtOpcUa.Driver.AbCip/AbCipDriver.cs

@@ -959,7 +959,8 @@ public sealed class AbCipDriver : IDriver, IReadable, IWritable, ITagDiscovery,
                                 : SecurityClassification.ViewOnly,
                             IsHistorized: false,
                             IsAlarm: false,
-                            WriteIdempotent: member.WriteIdempotent));
+                            WriteIdempotent: member.WriteIdempotent,
+                            Description: member.Description));
                     }
                     continue;
                 }
@@ -1019,7 +1020,8 @@ public sealed class AbCipDriver : IDriver, IReadable, IWritable, ITagDiscovery,
             : SecurityClassification.ViewOnly,
         IsHistorized: false,
         IsAlarm: false,
-        WriteIdempotent: tag.WriteIdempotent);
+        WriteIdempotent: tag.WriteIdempotent,
+        Description: tag.Description);
 
     /// <summary>Count of registered devices — exposed for diagnostics + tests.</summary>
     internal int DeviceCount => _devices.Count;