refactor: migrate {AccountActivity,BackendWebSocket}Service to @metamask/messenger

[cryptodev-2s]

Explanation

This PR migrates AccountActivityService and BackendWebSocketService to the new @metamask/messenger message bus, as opposed to the one exported from @metamask/base-controller.

References

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

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Note

Migrates AccountActivityService and BackendWebSocketService to the new @metamask/messenger, removing controller-messenger-specific exports and updating tests, dependencies, and configs.

• Messaging migration:
  • Replace RestrictedMessenger with new Messenger from @metamask/messenger in AccountActivityService and BackendWebSocketService.
  • Update tests to create root messenger, delegate actions/events, and use synchronous publish.
• Public API changes (BREAKING):
  • Remove exported controller-messenger-specific type aliases/constants (ACCOUNT_ACTIVITY_SERVICE_ALLOWED_*, *AllowedActions, *AllowedEvents) and stop re-exporting them in src/index.ts.
  • Update service messenger types to new Messenger generics.
• Dependencies & config:
  • Add @metamask/messenger; remove @metamask/base-controller. Update tsconfig references and yarn.lock.
• Docs:
  • CHANGELOG.md notes breaking changes and migration details.

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[Kriys94]

LGTM :)