Move bn.js to controller-utils dependencies

[FrederikBolding]

Explanation

This PR moves bn.js to be a non-dev dependency of controller-utils as it is used directly in https://github.com/MetaMask/core/blob/main/packages/controller-utils/src/util.ts

It also adds @types/bn.js to the dependencies, mirroring the implementation from assets-controllers.

For more context see this CI failure: https://github.com/MetaMask/snaps/actions/runs/8154723823/job/22288793408?pr=2245

Changelog

@metamask/controller-utils

• Changed: Add bn.js to dependencies

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 highlighted breaking changes using the "BREAKING" category above as appropriate