Move some functions into Utils::OS namespace

Also remove `Utils::Misc::getUserIDString()` since there are no use of
it.

src/base/utils/os.h

@@ -32,12 +32,41 @@
 
 #include <QtSystemDetection>
 
+#ifdef Q_OS_WIN
+#include <string>
+
+#include <windows.h>
+
+#include <QString>
+#endif
+
+#include "base/path.h"
+
+enum class ShutdownDialogAction;
+
 namespace Utils::OS
 {
+    void shutdownComputer(const ShutdownDialogAction &action);
+
 #ifdef Q_OS_MACOS
     bool isTorrentFileAssocSet();
     void setTorrentFileAssoc();
     bool isMagnetLinkAssocSet();
     void setMagnetLinkAssoc();
 #endif // Q_OS_MACOS
+
+#ifdef Q_OS_WIN
+    Path windowsSystemPath();
+
+    template <typename T>
+    T loadWinAPI(const QString &source, const char *funcName)
+    {
+        const std::wstring path = (windowsSystemPath() / Path(source)).toString().toStdWString();
+        return reinterpret_cast<T>(::GetProcAddress(::LoadLibraryW(path.c_str()), funcName));
+    }
+#endif // Q_OS_WIN
+
+#if defined(Q_OS_MACOS) || defined(Q_OS_WIN)
+    bool applyMarkOfTheWeb(const Path &file, const QString &url = {});
+#endif // Q_OS_MACOS || Q_OS_WIN
 }