Fix mempool.get_info, testmempoolaccept and outpoint.subscribe with the Palladium daemon

- mempool.get_info: the daemon has no incrementalrelayfee in getmempoolinfo,
  read incrementalfee from getnetworkinfo
- testmempoolaccept: the daemon does not report wtxid
- outpoint.subscribe: refuse the subscription (Coin.DAEMON_HAS_TXO_SPENDER_INDEX)
  instead of closing the session at the next block, when the daemon errors

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

tests/lib/test_palladium.py

@@ -46,6 +46,7 @@ def test_daemon_requirements_disabled():
     for coin, *_ in PARAMS:
         assert coin.MIN_REQUIRED_DAEMON_VERSION is None
         assert not coin.REQUIRED_DAEMON_INDEXES
+        assert coin.DAEMON_HAS_TXO_SPENDER_INDEX is False
 
 
 def bech32_encode_v0(hrp, program):