Separate to the prover, common, verifier and cli.
Rationale is that we'd like to be able to run the verifier without randomness, say on onchain targets (Solana SBF, WASM-based chains, etc.). Use the custom feature for getrandom in order to silence the linker when building for targets without support as the verifier doesn't need randomness anyway.
Add an onchain Cargo profile that can be used to compile such targets.
Also support cases in NTT where usize::BITS is not 64 for 2 adicity (e.g. WASM).
To test some of these targets, go to the verifier dir and:
Ref to now closed #206
Ref to now closed #206