Wizard has no 'Previous' buttons

[tyuldashev]

Description
All pages with exception of first one in the wizard has no 'Previous' buttons.

To Reproduce
Steps to reproduce the behavior:

1. Start 'Run UTBot: Quickstart Wizard' on Windows - note that it's first page, but has 'Previous' button
   
2. Click 'Next' button - note there is no 'Previous' button
   
3. Go through wizard, there is no 'Previous' buttons on the pages.

Expected behavior
Expected that all pages with exception of the first one has "Previous" button

Additional context
We should take into account that started on 'Linux' wizard would have another first page.