Add SliceUnpacker which consumes the bytes when unpacking

[Thoralf-M]

Description

            let unlock = Unlock::unpack_verified(&mut signature_bytes).map_err(|_| crate::Error::PackableError)?;
            // this should be done automatically if signature_bytes has SliceUnpacker type
            signature_bytes.drain(0..unlock.packed_len());

Motivation

Easier to use, better performance

Requirements

Unpacking from a SliceUnpacker should consume the bytes

Are you planning to do it yourself in a pull request?

No.

[Thoralf-M]

https://github.com/iotaledger/common-rs/pull/53/files