init: add exe name to bitcoind, bitcoin-node -version output to be able to distinguish these in tests

src/init/bitcoin-node.cpp

@@ -38,6 +38,7 @@ public:
     std::unique_ptr<interfaces::Echo> makeEcho() override { return interfaces::MakeEcho(); }
     interfaces::Ipc* ipc() override { return m_ipc.get(); }
     bool canListenIpc() override { return true; }
+    const char* exeName() override { return EXE_NAME; }
     node::NodeContext& m_node;
     std::unique_ptr<interfaces::Ipc> m_ipc;
 };