Use LIB_PREFIX in Rust bindings

[michaelsproul]

Extension of #313 to the Rust bindings.

[ppopth]

Is this still WIP?

[jtraglia]

So I don't love the new macros, but it's probably the best option we have. This PR is a good tradeoff of usability & minor changes to the codebase post-audit. I made a commit that fixes clang-format's complaints and alters the comments a little to match the style of others. The CI check that is failing is a known problem which we can ignore for now. LGTM 👍

[michaelsproul]

Still WIP on the Lighthouse integration unfortunately. We've hit a few linking issues that look like they might require further changes

[michaelsproul]

Ok, we've got it working reliably in Lighthouse now. I've pushed two commits here that seemed to help:

1. 5f3a7c1 moves the bindgen-generated Rust code to the Cargo build directory, rather than the source directory. This is the standard practice for bindgen and helps prevent strange caching behaviour when the c-kzg crate is compiled with different mainnet/minimal specs.
2. 6449e2c removes all unprefixed symbols from the generated object files. We were getting some link errors about symbols like blob_verify_kzg_proof being duplicated. These errors seemed to only occur occasionally, and only on Linux, and could actually have been a manifestation of (1). If you prefer not to make this change I can try reverting it and testing with (1) alone.

[divagant-martian]

I added the generated bindings to the source to be able to see them. So I don't think anyone else has an attachment to that setup. I'm fine with moving them to the build dir

[jtraglia]

Hey @michaelsproul I made a PR to your branch (michaelsproul#1) with some changes I'd like to make. I think this will simplify things a bit, but there were a lot of changes so I didn't feel comfortable committing them directly. Thoughts?

Also, tag @asn-d6 since this is based on your original PR.

[jtraglia]

Going to merge. I believe it's ready 👍