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/Import/L5kParser.cs

@@ -311,7 +311,8 @@ public static class L5kParser
 
         if (typePart.Length == 0) return null;
         var externalAccess = attributes.TryGetValue("ExternalAccess", out var ea) ? ea.Trim() : null;
-        return new L5kMember(name, typePart, arrayDim, externalAccess);
+        var description = attributes.TryGetValue("Description", out var d) ? Unquote(d) : null;
+        return new L5kMember(name, typePart, arrayDim, externalAccess, description);
     }
 
     // ---- helpers -----------------------------------------------------------
@@ -377,4 +378,9 @@ public sealed record L5kTag(
 public sealed record L5kDataType(string Name, IReadOnlyList<L5kMember> Members);
 
 /// <summary>One member line inside a UDT definition.</summary>
-public sealed record L5kMember(string Name, string DataType, int? ArrayDim, string? ExternalAccess);
+public sealed record L5kMember(
+    string Name,
+    string DataType,
+    int? ArrayDim,
+    string? ExternalAccess,
+    string? Description = null);