[Feature Request] Box<Type> should be std::unique_ptr<Type> in C++

[ludamad]

Hi! Thanks for maintaining this package.

🚀 Feature Request

Currently Box is just BigType in C++. This can cause very inefficient memory formats, as exemplified in the barretenberg library accidentally taking 7kb per opcode

Motivation

Reduce memory usage

Pitch

Describe the solution you'd like
Box be translated to unique_ptr

Describe alternatives you've considered
We can change to using Vec on Rust side instead of Box, but this removes static size guarantees

Are you willing to open a pull request? (See CONTRIBUTING)

Yes, I need pointers here as I don't see where Box is handled