[turbopack] Add `BumpVec` (vector implementation that takes a `Bump`) (#94296)
This PR implements `BumpVec` this is a custom vector implementation that
takes in a `Bump` as a type (from bumpalo) so that we get `Send`/`Sync`
on our `JSValue` vectors when we make that switch in:
https://github.com/vercel/next.js/pull/94297.