taprpc: add file anchor tx block hash to AssetTransfer

This commit introduces the anchor transaction block hash as a field in
the `AssetTransfer` RPC message. The `ListTransfers` RPC endpoint now
includes this block hash for each asset transfer, provided the anchor
transaction is confirmed. If the transaction is unconfirmed, this field
will remain unset.

Author: ffranr

rpcserver.go

@@ -3379,11 +3379,19 @@ func marshalOutboundParcel(
 	}
 
 	anchorTxHash := parcel.AnchorTx.TxHash()
+
+	// Marshal the anchor tx block hash.
+	var anchorTxBlockHashBytes []byte
+	parcel.AnchorTxBlockHash.WhenSome(func(hash chainhash.Hash) {
+		anchorTxBlockHashBytes = hash[:]
+	})
+
 	return &taprpc.AssetTransfer{
 		TransferTimestamp:  parcel.TransferTime.Unix(),
 		AnchorTxHash:       anchorTxHash[:],
 		AnchorTxHeightHint: parcel.AnchorTxHeightHint,
 		AnchorTxChainFees:  parcel.ChainFees,
+		AnchorTxBlockHash:  anchorTxBlockHashBytes,
 		Inputs:             rpcInputs,
 		Outputs:            rpcOutputs,
 	}, nil

taprpc/assetwalletrpc/assetwallet.swagger.json

@@ -871,6 +871,11 @@
             "$ref": "#/definitions/taprpcTransferOutput"
           },
           "description": "Describes the set of newly created asset outputs."
+        },
+        "anchor_tx_block_hash": {
+          "type": "string",
+          "format": "byte",
+          "description": "The block hash the contains the anchor transaction above. If unset, the\nanchor transaction is unconfirmed."
         }
       }
     },