Extract keccak-hasher crate

[kevinheavey]

Problem

solana_program::keccak imposes a solana_program dep on some SPL crates

Summary of Changes

• Move solana_program::keccak to a new crate solana-keccak-hasher, modelled on solana-sha256-hasher (see sdk: Extract hash and hasher crates #2015)
• This new crate should replace its Hash struct with solana_hash::Hash but it won't be able to do so without a breaking change. In the meantime I've just made it rely on solana_hash as much as possible while avoiding breakage

This branches off #3405 so that needs to be merged first