Start using init makeNode, makeChain, etc methods

Use interfaces::Init::make* methods instead of interfaces::Make*
functions, so interfaces can be constructed differently in different
executables without having to change any code. (So for example
bitcoin-gui can make an interfaces::Node pointer that communicates with
a bitcoin-node subprocess, while bitcoin-qt can make an interfaces::Node
pointer that starts node code in the same process.)

src/dummywallet.cpp

@@ -5,12 +5,14 @@
 #include <util/system.h>
 #include <walletinitinterface.h>
 
+class ArgsManager;
 class CWallet;
 
 namespace interfaces {
 class Chain;
 class Handler;
 class Wallet;
+class WalletClient;
 }
 
 class DummyWalletInit : public WalletInitInterface {
@@ -63,4 +65,9 @@ std::unique_ptr<Wallet> MakeWallet(const std::shared_ptr<CWallet>& wallet)
     throw std::logic_error("Wallet function called in non-wallet build.");
 }
 
+std::unique_ptr<WalletClient> MakeWalletClient(Chain& chain, ArgsManager& args)
+{
+    throw std::logic_error("Wallet function called in non-wallet build.");
+}
+
 } // namespace interfaces