Pass NodeContext, ConnMan, BanMan references more places

So g_connman and g_banman globals can be removed next commit.

src/node/context.cpp

@@ -0,0 +1,10 @@
+// Copyright (c) 2019 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <node/context.h>
+
+#include <interfaces/chain.h>
+
+NodeContext::NodeContext() {}
+NodeContext::~NodeContext() {}