Migrate `@metamask/utils` into core monorepo

[xinnanyemm]

The @metamask/utils package is rather large, and splitting it up into smaller packages would help us reduce the bundle size of various libraries that currently use it. However, doing so would make it more difficult to manage those smaller libraries. We should move it into this repo so that we can accomplish that.

See instructions for migrating a package to this repo here: https://github.com/MetaMask/core/blob/main/docs/package-migration-process-guide.md