Add wallet_name option to basicswap.json.

Removed "walletfile" setting for XMR and WOW, replaced with "wallet_name".
Set wallet_name in prepare script with eg: BTC_WALLET_NAME env var.

basicswap/interface/wow.py

@@ -1,6 +1,7 @@
 #!/usr/bin/env python
 # -*- coding: utf-8 -*-
 
+# Copyright (c) 2024 The Basicswap developers
 # Distributed under the MIT software license, see the accompanying
 # file LICENSE or http://www.opensource.org/licenses/mit-license.php.