Refactor view hierarchy to achieve dax dialog animation growing/shrinking

[alessandroboron]

Task/Issue URL: https://app.asana.com/0/1206329551987282/1207736844779819/f CC: @SabrinaTardio

Description:

This PR refactors the view hierarchy to make the UI Dialog seem to update the same view and match the Android animation. I also cleaned up a bit by moving/renaming some views.

https://github.com/duckduckgo/iOS/assets/1089358/cfdb15b1-021b-439d-815a-005b93ee4cda

Steps to test this PR:

1. Run the new Onboarding Intro flow
2. Check that the animation from the intro dialog to the browser comparison dialog looks nice and smooth.

Definition of Done (Internal Only):

• [ ] Does this PR satisfy our Definition of Done?

Copy Testing:

• [ ] Use of correct apostrophes in new copy, ie ’ rather than '

Orientation Testing:

• [ ] Portrait
• [ ] Landscape

Device Testing:

• [ ] iPhone SE (1st Gen)
• [ ] iPhone 8
• [ ] iPhone X
• [ ] iPhone 14 Pro
• [ ] iPad

OS Testing:

• [ ] iOS 15
• [ ] iOS 16
• [ ] iOS 17

Theme Testing:

• [ ] Light theme
• [ ] Dark theme

---

Internal references:

Software Engineering Expectations Technical Design Template

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