[RPC, Wallet] Move RPC dispatch table registration to wallet/ code

Allow extending the rpc dispatch table by appending commands when server is not running.

src/init.cpp

@@ -999,6 +999,8 @@ bool AppInit2(boost::thread_group& threadGroup, CScheduler& scheduler)
 
 #ifdef ENABLE_WALLET
     bool fDisableWallet = GetBoolArg("-disablewallet", false);
+    if (!fDisableWallet)
+        walletRegisterRPCCommands();
 #endif
 
     nConnectTimeout = GetArg("-timeout", DEFAULT_CONNECT_TIMEOUT);