multiprocess: Add new bitcoin-gui, bitcoin-qt, bitcoin-wallet init implementations

Add separate init implementations instead of sharing existing bitcoind
and bitcoin-node ones, so they can start to be differentiated in
upcoming commits with node and wallet code no longer linked into the
bitcoin-gui binary and wallet code no longer linked into the
bitcoin-node binary.

src/qt/bitcoin.cpp

@@ -13,7 +13,6 @@
 #include <interfaces/handler.h>
 #include <interfaces/init.h>
 #include <interfaces/node.h>
-#include <node/context.h>
 #include <node/ui_interface.h>
 #include <noui.h>
 #include <qt/bitcoingui.h>
@@ -462,9 +461,7 @@ int GuiMain(int argc, char* argv[])
     std::tie(argc, argv) = winArgs.get();
 #endif
 
-    NodeContext node_context;
-    int unused_exit_status;
-    std::unique_ptr<interfaces::Init> init = interfaces::MakeNodeInit(node_context, argc, argv, unused_exit_status);
+    std::unique_ptr<interfaces::Init> init = interfaces::MakeGuiInit(argc, argv);
 
     SetupEnvironment();
     util::ThreadSetInternalName("main");

src/qt/test/test_main.cpp

@@ -53,9 +53,7 @@ int main(int argc, char* argv[])
         BasicTestingSetup dummy{CBaseChainParams::REGTEST};
     }
 
-    NodeContext node_context;
-    int unused_exit_status;
-    std::unique_ptr<interfaces::Init> init = interfaces::MakeNodeInit(node_context, argc, argv, unused_exit_status);
+    std::unique_ptr<interfaces::Init> init = interfaces::MakeGuiInit(argc, argv);
     gArgs.ForceSetArg("-listen", "0");
     gArgs.ForceSetArg("-listenonion", "0");
     gArgs.ForceSetArg("-discover", "0");