Upgrade @metamask/signature-controller to version 34.0.0

A new major version of `@metamask/signature-controller`, 34.0.0, 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 checking the project's dependency manifests to confirm whether @metamask/signature-controller is present and identify its current version. Upgrade it to 34.0.0 if present, then run the existing project checks; done means the dependency is updated without regressions and the requested new features and bug fixes are unblocked.

Written by the indexing model from the issue text.