For each expected sighash, we collect a batch of public nonces from all verifiers. We aggregate and send aggregated nonce and all public nonces (needed for partial signature verification) to the agg_nonce_sender. Then repeat for the next sighash.
Collects partial signatures and corresponding public nonces from given stream and aggregates them.
Each partial signature will also be verified if PARTIAL_SIG_VERIFICATION is set to true.