Remove the RNG argument from Round::receive_message()

[fjarri]

Originally it was added to support a single ZK proof in synedrion where the verification required an RNG. The reason it did was to only pass it to crypto_primes::is_prime_with_rng(). After some consideration, I think it was not a correct way to handle that.

Since we want to be able to generate verifiable evidence for every receive_message() error, the outcome of receive_message() cannot be random (or we would have to store the RNG state which we don't have access to). If some of its internals need an RNG, it should construct one using shared_randomness, AssociatedData, or whatever else would be available during evidence verification, as a seed.

Specifically for primality checking, it seems that there is no need for an RNG at all (see entropyxyz/crypto-primes#21), although this method is too new and is not included in FIPS recommendations.

[coveralls]

Pull Request Test Coverage Report for Build 12617911790

Details

• 9 of 10 (90.0%) changed or added relevant lines in 5 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.1%) to 69.72%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
manul/src/combinators/chain.rs	3	4	75.0%

Totals
Change from base Build 12574035187:	-0.1%
Covered Lines:	1819
Relevant Lines:	2609

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💛 - Coveralls