fix: Updated confirmation page template layout

[ziggy-cyb]

Description

the layout for the confirmation page has changed in the GOV.UK design system, so this PR will change the layout of our confirmation page so that it matches.

• confirmationPage.customText.nextSteps will now appear above the "what happens next" title
• "What happens next" title will now only show if there are components underneath it.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• This change requires a documentation update

How Has This Been Tested?

• Manual testing with different form jsons (attached)

Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation and versioning
• I have updated the architecture diagrams as per Contribute.md OR added an architectural decision record entry

form-with-components.json
form-with-next-steps.json
form-without-next-steps.json