Move to program ID and DB key of SP1 `vk` hash

We use a sha256 hash of the ELF presently to store the setup of the sp1 client per program.

The Poseidon hash of the program's view key is the canonical ID for the compiled ELF, rather than the hash of the ELF itself. This is how we can check if #5 is respected. Thus to close this issue we need to check in CI if this changes from build to build. Suggest we use the included `./zkVM/sp1/src/bin/vkey.rs` bin for that purpose.

See https://docs.rs/sp1-sdk/latest/sp1_sdk/struct.SP1VerifyingKey.html#method.hash_bytes