Detect tails, support data persistence

Co-authored-by: Thotbot <thotbot@protonmail.com>
Co-authored-by: Selsta <selsta@sent.at>

src/qt/TailsOS.h

@@ -0,0 +1,23 @@
+#ifndef TAILSOS_H
+#define TAILSOS_H
+
+#include <QApplication>
+
+
+class TailsOS
+{
+public:
+    TailsOS();
+    static bool detect();
+    static bool detectDataPersistence();
+    static bool detectDotPersistence();
+
+    static void showDataPersistenceDisabledWarning();
+    static void askPersistence();
+    static void persistXdgMime(QString filePath, QString data);
+
+    static bool usePersistence;
+    static QString tailsPathData;
+};
+
+#endif // TAILSOS_H