Split Omnibar: Settings screen

[0nko]

Task/Issue URL: https://app.asana.com/1/137249556945/project/488551667048375/task/1211565479656356?focus=true

Description

This PR updates the Appearance settings screen with the new pictograms and includes the split omnibar option.

Steps to test this PR

Figma design for reference: Figma

Old settings

• Go to Settings -> Appearance
• Verify the old omnibar position is displayed

New settings

• Enable splitOmnibar in the feature flags
• Go to Settings -> Appearance
• Verify the new omnibar type pictograms are displayed
• Verify the correct omnibar type is selected
• Try changing the current type for each option
• Verify the new type is visually selected
• Leave the Appearance settings and come back
• Verify the previous selection is restored

Dark mode

• Change the theme to dark mode
• Verify new dark pictograms are used
• Select each option and verify the dark-mode selection options are show

Omnibar type fallback when feature disabled

• Go to Settings -> Appearance
• Change the omnibar type to Split
• Go to the feature flag settings
• Disable the useUnifiedOmnibar feature
• Restart the app
• Go to Settings -> Appearance
• Verify the omnibar position is set to Top

UI changes

Before	After

[0nko]

• Split Omnibar: Ship review changes #7083
• Split Omnibar: Existing functionality integration #7062
• Split Omnibar: Tab switcher bottom bar #7056
• Split Omnibar: Remove old feature flag #7045
• Split Omnibar: Address bar integration #7042
• Split Omnibar: Bottom navigation #7032
• Split Omnibar: Settings screen #7002 👈 (View in Graphite)
• Split Omnibar: Data type & storage update #6991
• Split Omnibar: Omnibar layout refactoring #6983
• develop

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[LukasPaczos]

LGTM