Include C++ implementations of BoringSSL algorithms

[fpseverino]

In BoringSSL some algorithms, like ML-KEM and ML-DSA, are written in C++, but the vendor-boringssl.sh script doesn't look for .cc files inside BoringSSL’s crypto directory.

New Issue Checklist

• I'm using the latest version of Swift Crypto (main branch)
• I read the Contribution Guidelines
• I searched for existing GitHub issues

Expected behavior

Being able to use methods from algorithms written in C++

Actual behavior

Not being able to use methods from algorithms written in C++

Steps to reproduce

1. Add the header file of an algorithm written in C++ inside Sources/CCryptoBoringSSL/include/CCryptoBoringSSL.h
2. Import CCryptoBoringSSL
3. Try to use a CCryptoBoringSSL_xxx method of an algorithm written in C++

Swift Crypto version/commit hash

commit: ff0f781

Environment

Swift version: Apple Swift version 6.0.2 (swiftlang-6.0.2.1.2 clang-1600.0.26.4)
Target: arm64-apple-macosx15.0
Unix version: Darwin MacBookPro.wind3.hub 24.1.0 Darwin Kernel Version 24.1.0: Thu Oct 10 21:05:14 PDT 2024
 root:xnu-11215.41.3~2/RELEASE_ARM64_T8103 arm64
macOS version: 15.1.1

Xcode-select path: '/Applications/Xcode.app/Contents/Developer

Xcode: Xcode 16.1 (Build version 16B40)

[Lukasa]

Thanks for filing this @fpseverino! Let's nail this down before we move forward on #278 and #267, as I'd like us to make sure we aren't going to regress those.

[fpseverino]

I agree @Lukasa! This will need a BoringSSL update too, right? Is it something that I can/should do?

[Lukasa]

It's going to be a lot easier for me to do it than you, I suspect

[fpseverino]

All right, just to clarify, would you also take care of updating the script or would you prefer me to do it?

[Lukasa]

I can update the script as well. 😄

[Lukasa]

Huh, turns out that we timed this work well, as that immediately became 100% necessary! https://boringssl.googlesource.com/boringssl/+/5813c2c10c73d800f1b0d890a7d74ff973abbffc