Add BTC descriptor wallet support.

Set BTC_USE_DESCRIPTORS env var to true to enable descriptors in the prepare script and test_btc_xmr
A separate watchonly wallet is created when using descriptor wallets.

tests/basicswap/common_xmr.py

@@ -6,26 +6,23 @@
 # Distributed under the MIT software license, see the accompanying
 # file LICENSE or http://www.opensource.org/licenses/mit-license.php.
 
-import os
-import sys
 import json
+import logging
+import multiprocessing
+import os
 import shutil
 import signal
-import logging
-import unittest
+import sys
 import threading
-import multiprocessing
+import unittest
 from io import StringIO
 from urllib.request import urlopen
 from unittest.mock import patch
 
-from basicswap.rpc_xmr import (
-    callrpc_xmr,
-)
+from basicswap.contrib.rpcauth import generate_salt, password_to_hmac
+from basicswap.rpc_xmr import callrpc_xmr
 from tests.basicswap.mnemonics import mnemonics
-from tests.basicswap.util import (
-    waitForServer,
-)
+from tests.basicswap.util import waitForServer
 from tests.basicswap.common import (
     BASE_PORT,
     BASE_RPC_PORT,
@@ -35,6 +32,7 @@ from tests.basicswap.common import (
     LTC_BASE_PORT,
     LTC_BASE_RPC_PORT,
     PIVX_BASE_PORT,
+    BTC_USE_DESCRIPTORS,
 )
 from tests.basicswap.extended.test_dcr import (
     DCR_BASE_PORT,
@@ -49,8 +47,6 @@ from tests.basicswap.extended.test_doge import (
     DOGE_BASE_RPC_PORT,
 )
 
-from basicswap.contrib.rpcauth import generate_salt, password_to_hmac
-
 import basicswap.config as cfg
 import basicswap.bin.run as runSystem
 
@@ -133,6 +129,7 @@ def run_prepare(
     os.environ["PART_RPC_PORT"] = str(PARTICL_RPC_PORT_BASE)
     os.environ["BTC_RPC_PORT"] = str(BITCOIN_RPC_PORT_BASE)
     os.environ["BTC_PORT"] = str(BITCOIN_PORT_BASE)
+    os.environ["BTC_USE_DESCRIPTORS"] = str(BTC_USE_DESCRIPTORS)
     os.environ["LTC_RPC_PORT"] = str(LITECOIN_RPC_PORT_BASE)
     os.environ["DCR_RPC_PORT"] = str(DECRED_RPC_PORT_BASE)
     os.environ["FIRO_RPC_PORT"] = str(FIRO_RPC_PORT_BASE)