lnpeermgr: add_peer: fix check if proxy enabled

LNPeerManager.add_peer would only check if self.network.proxy is set,
which it is always as Network is initialized with self.proxy =
ProxySettings(). Instead it should check if proxy is set and enabled.

tests/test_lnpeer.py

@@ -26,7 +26,7 @@ from electrum import bitcoin
 from electrum import util
 from electrum import constants
 from electrum import bip32
-from electrum.network import Network
+from electrum.network import Network, ProxySettings
 from electrum import simple_config, lnutil
 from electrum.lnaddr import lnencode, LnAddr, lndecode
 from electrum.bitcoin import COIN, sha256
@@ -71,6 +71,7 @@ class MockNetwork:
         self.path_finder = LNPathFinder(self.channel_db)
         self.lngossip = MockLNGossip()
         self.tx_queue = asyncio.Queue()
+        self.proxy = ProxySettings()
         self._blockchain = MockBlockchain()
 
     def get_local_height(self):