feat: add BytecodeLocked::original_bytecode

[DaniPopes]

If someone wants a Bytes of the original bytecode they have to copy it with Bytes::copy_from_slice, but we store it already as Bytes so we can use Bytes::slice to avoid copying it.

E.g: https://github.com/foundry-rs/foundry/blob/f11da382d69ee7df32c56290101f6ef5e0cf9317/crates/evm/coverage/src/inspector.rs#L17