This change will split common folder to four different folders:
Linux, Unix, Windows and MacOS. Each of these folders includes scripts
which are common for their operating system familes

Task-number: QTQAINFRA-1451
Change-Id: Ic93b2183052335dee875d1452b21e38d268b6474
Reviewed-by: Jędrzej Nowacki <jedrzej.nowacki@qt.io>