Rewrite 7z uncompressing to work on all supported platforms

On Windows we ship 7za.exe in our binaries.
On MacOS we do the same, but the executable needs to be called with the full path.
On Linux we don't ship anything but assume it to be available from the distribution.

src/blackmisc/compressutils.h

@@ -16,19 +16,23 @@
 #include <QByteArray>
 #include <QStringList>
 
+class QProcess;
+
 namespace BlackMisc
 {
     //! Compress utilities
     class BLACKMISC_EXPORT CCompressUtils
     {
     public:
+        CCompressUtils() = delete;
+
         //! Length header
         //! \remark 4 bytes -> 32bit
         static QByteArray lengthHeader(qint32 size);
 
         //! Unzip my using 7zip
         //! \remark relies on external 7zip command line
-        static bool zip7Uncompress(const QString &file, const QString &directory, bool wait, QStringList *stdOutAndError = nullptr);
+        static bool zip7Uncompress(const QString &file, const QString &directory, QStringList *stdOutAndError = nullptr);
 
         //! External program existing?
         //! \remark relies on external 7zip command line
@@ -39,9 +43,10 @@ namespace BlackMisc
         static bool whichZip7(QStringList *stdOutAndError = nullptr);
 
     private:
-        //! Ctor
-        CCompressUtils() {}
+        static bool runZip7Process(QProcess *zipProcess, QStringList *stdOutAndError);
+
     };
 } // ns
 
 #endif // guard
+