feat: add general settings to core PreferencesController

[fabiobozzo]

Explanation

Current State

MetaMask's general settings (theme, locale, currency, etc.) are currently managed differently across platforms:

• Extension: Stored in the extension's PreferencesController
• Mobile: Managed through Redux state

This architectural difference creates challenges for implementing cross-platform settings synchronization, as there's no single source of truth for these preferences.

Solution

This PR adds general settings properties to the core PreferencesController to establish a centralized foundation for settings sync:

• currentLocale - User's preferred language
• theme - UI theme preference (light/dark/auto)
• useBlockie - Identicon style preference
• currentCurrency - Display currency for fiat conversions
• showNativeTokenAsMainBalance - Balance display preference
• hideZeroBalanceTokens - Token list filtering preference

Each property includes:

• Appropriate default values
• Setter methods following existing patterns
• Full JSDoc documentation
• Comprehensive test coverage

Next Steps

This lays the groundwork for unified settings management:

• Extension: Will be updated to consume these settings from the core controller instead of maintaining its own copies
• Mobile: Will bridge these settings from Redux state to the core controller for synchronization

This approach ensures all platforms use a consistent source of truth while maintaining backward compatibility during the transition.

References

IDENTITY-172

Checklist

• I've updated the test suite for new or updated code as appropriate
• I've updated documentation (JSDoc, Markdown, etc.) for new or updated code as appropriate
• I've communicated my changes to consumers by updating changelogs for packages I've changed, highlighting breaking changes as necessary
• I've prepared draft pull requests for clients and consumer packages to resolve any breaking changes

[fabiobozzo]

@metamaskbot publish-preview

[github-actions]

Preview builds have been published. See these instructions for more information about preview builds.

Expand for full list of packages and versions.

{
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  "@metamask-previews/accounts-controller": "31.0.0-preview-32f9004a",
  "@metamask-previews/address-book-controller": "6.1.1-preview-32f9004a",
  "@metamask-previews/announcement-controller": "7.0.3-preview-32f9004a",
  "@metamask-previews/app-metadata-controller": "1.0.0-preview-32f9004a",
  "@metamask-previews/approval-controller": "7.1.3-preview-32f9004a",
  "@metamask-previews/assets-controllers": "71.0.0-preview-32f9004a",
  "@metamask-previews/base-controller": "8.0.1-preview-32f9004a",
  "@metamask-previews/bridge-controller": "35.0.0-preview-32f9004a",
  "@metamask-previews/bridge-status-controller": "35.0.0-preview-32f9004a",
  "@metamask-previews/build-utils": "3.0.3-preview-32f9004a",
  "@metamask-previews/chain-agnostic-permission": "1.0.0-preview-32f9004a",
  "@metamask-previews/composable-controller": "11.0.0-preview-32f9004a",
  "@metamask-previews/controller-utils": "11.11.0-preview-32f9004a",
  "@metamask-previews/delegation-controller": "0.5.0-preview-32f9004a",
  "@metamask-previews/earn-controller": "3.0.0-preview-32f9004a",
  "@metamask-previews/eip1193-permission-middleware": "1.0.0-preview-32f9004a",
  "@metamask-previews/ens-controller": "17.0.1-preview-32f9004a",
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  "@metamask-previews/eth-json-rpc-provider": "4.1.8-preview-32f9004a",
  "@metamask-previews/foundryup": "1.0.0-preview-32f9004a",
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  "@metamask-previews/json-rpc-middleware-stream": "8.0.7-preview-32f9004a",
  "@metamask-previews/keyring-controller": "22.1.0-preview-32f9004a",
  "@metamask-previews/logging-controller": "6.0.4-preview-32f9004a",
  "@metamask-previews/message-manager": "12.0.2-preview-32f9004a",
  "@metamask-previews/multichain-api-middleware": "1.0.0-preview-32f9004a",
  "@metamask-previews/multichain-network-controller": "0.9.0-preview-32f9004a",
  "@metamask-previews/multichain-transactions-controller": "3.0.0-preview-32f9004a",
  "@metamask-previews/name-controller": "8.0.3-preview-32f9004a",
  "@metamask-previews/network-controller": "24.0.0-preview-32f9004a",
  "@metamask-previews/notification-services-controller": "14.0.0-preview-32f9004a",
  "@metamask-previews/permission-controller": "11.0.6-preview-32f9004a",
  "@metamask-previews/permission-log-controller": "3.0.3-preview-32f9004a",
  "@metamask-previews/phishing-controller": "13.0.0-preview-32f9004a",
  "@metamask-previews/polling-controller": "14.0.0-preview-32f9004a",
  "@metamask-previews/preferences-controller": "18.4.1-preview-32f9004a",
  "@metamask-previews/profile-sync-controller": "21.0.0-preview-32f9004a",
  "@metamask-previews/rate-limit-controller": "6.0.3-preview-32f9004a",
  "@metamask-previews/remote-feature-flag-controller": "1.6.0-preview-32f9004a",
  "@metamask-previews/sample-controllers": "1.0.0-preview-32f9004a",
  "@metamask-previews/seedless-onboarding-controller": "2.0.1-preview-32f9004a",
  "@metamask-previews/selected-network-controller": "23.0.0-preview-32f9004a",
  "@metamask-previews/signature-controller": "31.0.1-preview-32f9004a",
  "@metamask-previews/token-search-discovery-controller": "3.3.0-preview-32f9004a",
  "@metamask-previews/transaction-controller": "58.1.1-preview-32f9004a",
  "@metamask-previews/user-operation-controller": "37.0.0-preview-32f9004a"
}

[mathieuartu]

Where are those default values coming from?