perf(account-tree-controller): use batched account events

[ccharly]

Explanation

Use new :accounts{Added,Removed} events from the AccountsController.

References

N/A

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
• I've introduced breaking changes in this PR and have prepared draft pull requests for clients and consumer packages to resolve them

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Note

Medium Risk
Switching from single-account to batched AccountsController events changes the controller’s event contract and could cause missed tree/selection updates if any publisher/consumer still emits or expects the old events. Batched removal also changes when selectedAccountGroupChange is emitted, so regressions would show up as incorrect auto-selection after removals.

Overview
Account add/remove handling is migrated to the new batched AccountsController:accountsAdded / accountsRemoved events. The controller now filters out already-known accounts/unknown removals and performs inserts/removals within a single update call, emitting AccountTreeController:accountTreeChange once per batch.

Selection-change emission is adjusted for batched removals. selectedAccountGroupChange is now published only after the batch update when the selected group actually differs from the pre-batch value.

Tests, messenger mocks, and AllowedEvents typings are updated to use the new event names/payload shapes, and the package changelog notes the change.

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[hmalik88]

nice