lnrpc: add read onchain permissions to invoice.macaroon

rpcserver.go

@@ -155,6 +155,10 @@ var (
 			Entity: "address",
 			Action: "write",
 		},
+		{
+			Entity: "onchain",
+			Action: "read",
+		},
 	}
 
 	// permissions maps RPC calls to the permissions they require.