Add generic IPC mechanism between Lua envs

src/script/lua_api/l_ipc.h

@@ -0,0 +1,15 @@
+// Minetest
+// SPDX-License-Identifier: LGPL-2.1-or-later
+
+#pragma once
+
+#include "lua_api/l_base.h"
+
+class ModApiIPC : public ModApiBase {
+private:
+	static int l_ipc_get(lua_State *L);
+	static int l_ipc_set(lua_State *L);
+
+public:
+	static void Initialize(lua_State *L, int top);
+};