refactor: migrate ShieldController to @metamask/messenger

[cryptodev-2s]

Explanation

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

References

• Related to Implement messenger delegation #5626

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

---

Note

Migrates ShieldController to @metamask/messenger, adds getState action, renames metadata key, and updates tests and configs accordingly.

• Shield Controller:
  • Migrate to @metamask/messenger (replace RestrictedMessenger; switch to messenger.subscribe/publish/unsubscribe; import controller types from @metamask/base-controller/next).
  • Add ShieldControllerGetStateAction and export via src/index.ts.
  • Rename metadata key anonymous to includeInDebugSnapshot.
  • Update tests to new messenger API: introduce rootMessenger, adjust mocks and utils to use @metamask/messenger.
  • Add dependency @metamask/messenger; include TS references to packages/messenger.
• Docs/Changelog/Graph:
  • Update changelog with added action and BREAKING changes.
  • README dependency graph: add shield_controller --> messenger and eip_7702_internal_rpc_middleware --> controller_utils.

^{Written by Cursor Bugbot for commit 3e00774. This will update automatically on new commits. Configure here.}

[mcmire]

LGTM!