[bug]: `netlify dev` fails to run middleware

[orinokai]

Since shipping the PR to vendor Deno dependencies, netlify dev no longer runs middleware or edge functions correctly.

#2302

To fix this, we should ensure the vendored dependencies are copied to the dev server directory during onPreDev

This is the build step that does the vendoring: https://github.com/netlify/next-runtime/pull/2302/files#diff-126513369bd4ea319345bbb81971f82857aecab4d597bf4e0063f7dd07082b3a

Added to Linear as FRA-53.

[serhalp]

@orinokai Is this still valid for v5?

[serhalp]

Completed long ago by #2341