Upgrade @metamask/account-tree-controller to version 2.0.0

A new major version of `@metamask/account-tree-controller`, 2.0.0, is now available. This issue has been assigned to you and your team because you code-own this package in the `core` repo. If this package is present in this project, please prioritize upgrading it soon to unblock new features and bugfixes.

Start by locating the dependency declaration and usages of @metamask/account-tree-controller in the repository, then review the package's 2.0.0 release notes for breaking changes. Update the dependency and affected usages, and run the relevant project checks to confirm the extension builds and its tests pass.

Written by the indexing model from the issue text.