copy found mods to instance (FTB and Flame)

Signed-off-by: Rachel Powers <508861+Ryex@users.noreply.github.com>

launcher/FileSystem.h

@@ -75,6 +75,8 @@ bool ensureFilePathExists(QString filenamepath);
  */
 bool ensureFolderPathExists(QString filenamepath);
 
+bool copyFile(QString &src, QString &dst);
+
 class copy {
    public:
     copy(const QString& src, const QString& dst)