a1d464b50d
Replace value?.ToString() with AttributeValueCodec.Encode(value) in
AttributeAccessor indexer set and SetAsync, so a List<string>{"a","b"}
encodes to ["a","b"] instead of the garbage ToString representation.
Add using ZB.MOM.WW.ScadaBridge.Commons.Types. Tests verify the codec
contract (list→JSON array, scalar passthrough, null); full round-trip
through the accessor is not viable without a live Akka ActorSystem —
noted in-test with explanation.