UI iteration on the encryption settings

[bmarty]

Content

Iterate on crypto screen, UX flow and wording, so that it matches what has been designed at https://www.figma.com/design/qTWRfItpO3RdCjnTKPu4mL/Settings?node-id=1651-24968&node-type=canvas&m=dev

Motivation and context

Closes #3737 Closes #3738 Closes #3739

Screenshots / GIFs

https://github.com/user-attachments/assets/a7b6dc18-0aee-43af-a388-9f115bd1ea41

Tests

• Play with the "Encryption" settings and observe that the flow is similar to what's in Figma.

Tested devices

• [ ] Physical
• [x] Emulator
• OS version(s):

Checklist

• [ ] Changes have been tested on an Android device or Android emulator with API 23
• [ ] UI change has been tested on both light and dark themes
• [ ] Accessibility has been taken into account. See https://github.com/element-hq/element-x-android/blob/develop/CONTRIBUTING.md#accessibility
• [ ] Pull request is based on the develop branch
• [ ] Pull request title will be used in the release note, it clearly define what will change for the user
• [ ] Pull request includes screenshots or videos if containing UI changes
• [ ] Pull request includes a sign off
• [ ] You've made a self review of your PR

[github-actions[bot]]

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[codecov[bot]]

Codecov Report

Attention: Patch coverage is 84.00000% with 24 lines in your changes missing coverage. Please review.

Project coverage is 82.98%. Comparing base (e329370) to head (405543a). Report is 30 commits behind head on develop.

Files with missing lines	Patch %	Lines
...res/securebackup/impl/root/SecureBackupRootView.kt	66.66%	19 Missing and 3 partials :warning:
...es/securebackup/impl/root/SecureBackupRootState.kt	66.66%	1 Missing and 1 partial :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## develop #3750 +/- ## =========================================== - Coverage 83.05% 82.98% -0.07% =========================================== Files 1754 1749 -5 Lines 43994 43973 -21 Branches 5142 5154 +12 =========================================== - Hits 36539 36492 -47 - Misses 5632 5656 +24 - Partials 1823 1825 +2 ```

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[americanrefugee]

I mentioned 2 issues on #2590:

1. After generating/saving the recovery key and clicking "Done", the user should see this confirmation page.
2. After setting up the recovery key, the Settings menu item should simply say "Change recovery key" without any additional help text.

[sonarcloud[bot]]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[bmarty]

Discussion was in #2590, so I think there is no blockers from @americanrefugee anymore.