feat(nargo): Leverage rustls instead of openssl for downloads

[phated]

Related issue(s)

Description

(Currently a draft to discuss) This updates the aztec_backend package to point at my commit in noir-lang/acvm-backend-barretenberg#46 - which replaces the openssl dependency with rustls. This is a dependency that doesn't require openssl to exist on a system, and helps with cross-compilation. I found out that they don't have complete support (e.g. RISC-V is unsupported) but they seem to support all the platforms we really care about.

This allows us to remove a hack that we have in the build-nargo workflows to cross-compile the linux binaries.

Summary of changes

Updates aztec_backend, which still needs to be reviewed and merged upstream.

Dependency additions / changes

aztec_backend

Test additions / changes

Checklist

• I have tested the changes locally.
• I have formatted the changes with Prettier and/or cargo fmt with default settings.
• I have linked this PR to the issue(s) that it resolves.
• I have reviewed the changes on GitHub, line by line.
• I have ensured all changes are covered in the description.

Additional context

[jfecher]

I'm a fan of removing the requirement for users to have openssl. It is a common error that is encountered when trying to build noir from source that it is missing. It is not as important now that binaries are being emphasized but I still think it is good to have building from source be as easy as possible.