[iOS] Add alternative app icons

[kylehickinson]

Resolves brave/brave-browser#43141

Submitter Checklist:

• I confirm that no security/privacy review is needed and no other type of reviews are needed, or that I have requested them
• There is a ticket for my issue
• Used Github auto-closing keywords in the PR description above
• Wrote a good PR/commit description
• Squashed any review feedback or "fixup" commits before merge, so that history is a record of what happened in the repo, not your PR
• Added appropriate labels (QA/Yes or QA/No; release-notes/include or release-notes/exclude; OS/...) to the associated issue
• Checked the PR locally:
  • npm run test -- brave_browser_tests, npm run test -- brave_unit_tests wiki
  • npm run presubmit wiki, npm run gn_check, npm run tslint
• Ran git rebase master (if needed)

Reviewer Checklist:

• A security review is not needed, or a link to one is included in the PR description
• New files have MPL-2.0 license header
• Adequate test coverage exists to prevent regressions
• Major classes, functions and non-trivial code blocks are well-commented
• Changes in component dependencies are properly reflected in gn
• Code follows the style guide
• Test plan is specified in PR before merging

After-merge Checklist:

• The associated issue milestone is set to the smallest version that the
  changes has landed on
• All relevant documentation has been updated, for instance:
  • https://github.com/brave/brave-browser/wiki/Deviations-from-Chromium-(features-we-disable-or-remove)
  • https://github.com/brave/brave-browser/wiki/Proxy-redirected-URLs
  • https://github.com/brave/brave-browser/wiki/Fingerprinting-Protections
  • https://github.com/brave/brave-browser/wiki/Brave%E2%80%99s-Use-of-Referral-Codes
  • https://github.com/brave/brave-browser/wiki/Web-Compatibility-Exceptions-in-Brave
  • https://github.com/brave/brave-browser/wiki/QA-Guide
  • https://github.com/brave/brave-browser/wiki/P3A

Test Plan:

[github-actions]

[puLL-Merge] - brave/brave-core@27183

Description

This PR adds support for alternate app icons in the Brave iOS app. It introduces a new settings page where users can choose from a variety of custom app icons, including themed and nostalgic designs.

Changes

Changes

1. Client.xcodeproj/project.pbxproj:

   • Added ASSETCATALOG_COMPILER_ALTERNATE_APPICON_NAMES to include the new alternate icon names.

2. New asset files:

   • Added multiple new .appiconset directories and .png files for each alternate icon.

3. AltIconsModel.swift:

   • Created a new model to manage the alternate icons and handle icon selection.

4. AltIconsView.swift:

   • Implemented a SwiftUI view to display and allow selection of alternate icons.

5. SettingsViewController.swift:

   • Integrated the new alternate icons feature into the settings menu.
   • Added a new row in the display section for changing the app icon.
   • Implemented AppIconCell for custom icon display in the settings.

6. BraveStrings.swift:

   • Added new localized strings for the alternate icons feature.

sequenceDiagram
    participant User
    participant SettingsViewController
    participant AltIconsView
    participant AltIconsModel
    participant UIApplication

    User->>SettingsViewController: Taps "Change App Icon"
    SettingsViewController->>AltIconsView: Present AltIconsView
    User->>AltIconsView: Selects new icon
    AltIconsView->>AltIconsModel: setAlternateAppIcon(icon)
    AltIconsModel->>UIApplication: setAlternateIconName(iconName)
    UIApplication-->>AltIconsModel: Icon change result
    AltIconsModel-->>AltIconsView: Update UI
    AltIconsModel-->>SettingsViewController: Notify of icon change
    SettingsViewController->>SettingsViewController: Update icon in settings list

Loading

Possible Issues

• The PR doesn't include any fallback mechanism if an alternate icon fails to load, which could potentially lead to a blank icon if the asset is missing or corrupted.

Security Hotspots

None identified. The changes are primarily UI-related and don't involve sensitive data handling or security-critical operations.