Refactor logic when creating extension via CLI

[TimonCzech]

Summary

Refactored the code so it now creates a new extension request with the version 999-snapshot

Please check the relevant options

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Dependency update
• [x] Refactoring
• [ ] Release (follows conventions described in the RELEASE.md)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)
• [ ] This change requires a documentation update
• [ ] This change requires execution against OCP (use run tests phrase in comment)

Checklist:

• [x] Example scenarios has been updated / added
• [x] Methods and classes used in PR scenarios are meaningful
• [x] Commits are well encapsulated and follow the best practices

[michalvavrik]

Thanks @TimonCzech , I am not sure, but don't have time to invest ATM. @jedla97 please check thoroughly

[jedla97]

CI is green, so merging.