Cargo vendor with c-kzg crate(s)

[realbigsean]

Description

Since we import the same dependency twice with different features enabled in kzg, we are no longer able to vendor lighthouse deps due to this issue: rust-lang/cargo#10310

It looks like there was previously a --no-merge-sources flag, but when vendor was added as a subcommand to cargo this was removed. There still exists cargo-vendor vendor --no-merge-sources but I think this requires using rust edition 2018. I wonder if separately publishing the kzg crate or publishing a mainnet and minimal version of the c-kzg bindings might let us workaround this?

[realbigsean]

The only workaround I've been able to find in the wild is to publish the same source with different features enabled based on the package name: https://github.com/bodil/im-rs/blob/71331eadac64654bc56f598647ab544197cb1319/build.rs#L14

We would have to make a similar change to the c-kzg-4844 rust bindings

cargo vendor de-dupes based on package name + version which is why this works

[realbigsean]

this will be resolved when we can integrate these changes: ethereum/c-kzg-4844#363

[realbigsean]

resolved in #4886