Upgrade @metamask/signature-controller to version 39.0.0

A new major version of `@metamask/signature-controller`, 39.0.0, 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 in the metamask-mobile repository by checking whether @metamask/signature-controller is present and locating its current version. Review the dependency's upgrade impact and project checks; done means the project uses version 39.0.0 successfully and the update does not block the referenced features or bug fixes.

Written by the indexing model from the issue text.