feat(cat-voices): registration flow placeholders

[dtscalac]

Description

Adds placeholders with next/back button to not yet implemented steps in registration.

Refers #818

Please confirm the following checks

• [x] My code follows the style guidelines of this project
• [x] I have performed a self-review of my code
• [x] I have commented my code, particularly in hard-to-understand areas
• [x] I have made corresponding changes to the documentation
• [x] My changes generate no new warnings
• [x] I have added tests that prove my fix is effective or that my feature works
• [x] New and existing unit tests pass locally with my changes
• [x] Any dependent changes have been merged and published in downstream module

[github-actions[bot]]

✅ Test Report | ${\color{lightgreen}Pass: 277/277}$ | ${\color{red}Fail: 0/277}$ |