feat(csprng): Native AES for Apple Silicon

[tmontaigu]

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Resolves: zama-ai/concrete-core-internal#117

Description

The goal is to support AppleSilicon chip natively in concrete-csprng.

This implements AES encryption using aarch64 native instructions from the aes and neon features which are part of the ARMv8.0-A spec.

However, the x86_64 rdseed feature only has an equivalent in ARMv8.5-A, and M1 chip are ARMv8.4-A and Rust does not seem to expose this feature in the core::arch::aarch64.

So we use the Apple specific API to generate cryptographically secure random numbers instead.

There is one drawback however: This change requires nightly to be compiled (but only on Apple Silicon macs)