fix: various UI issues in Backup/Restore - WPB-16078

[caldrian]

WPB-16078 [iOS, iPad] Minor left-over bugs in Backup/Restore

Issue

This PR attempts to fix a few left-over issues, like

• the height of sheets
• little issues like the password text field losing focus when tapping the toggle button
• accent color propagation to the new sheets
• accessibility label for toggle password visibility icon

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Checklist

• Title contains a reference JIRA issue number like [WPB-XXX].
• Description is filled and free of optional paragraphs.
• Adds/updates automated tests.

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UI accessibility checklist

If your PR includes UI changes, please utilize this checklist:

• Make sure you use the API for UI elements that support large fonts.
• All colors are taken from WireDesign.ColorTheme or constructed using WireDesign.BaseColorPalette.
• New UI elements have Accessibility strings for VoiceOver.

[github-actions]

Test Results

    4 files     14 suites   4m 40s ⏱️
3 263 tests 3 234 ✅ 29 💤 0 ❌
3 273 runs  3 244 ✅ 29 💤 0 ❌

Results for commit bd75a1d.

♻️ This comment has been updated with latest results.