Generalize sha2-256 zkLLVM SDK interface

[nkaskov]

We have an intrinsic for sha2-256, but its interface differs from the interfaces of native sha2-256. We need to either update intrinsic's interface or extend sha2-256 circuit interface with proper intrinsic call, so it will allow to call hash from arbitrary byte-blob (we can start with supporting std::array<std::uint, ContainerSize> hashing).