Windows Script Host (cscript) may not be available

The Windows Script Host (cscript) may not be available on Windows systems. For example it may be disabled or there may be no script engine for vbs files.

There are two methods in /src/libs/installer/packagemanagercore_p.cpp file which utilizes cscript to delete and rename files. May be it's a good idea not to rely on cscript at all.