Function create_consumer_registration_params 

pub fn create_consumer_registration_params(
    consumer_pair: &Pair,
    consumer_account: &[u8; 32],
    verifier_account: &[u8; 32],
) -> Value

Builds consumer registration parameters for create_attest_call

The LiteConsumerRegistrationParams struct has fields: signature: MultiSignature, account: AccountId, identifier_key: CommunicationIdentifier ([u8; 65]), username: Username (BoundedVec<u8, 32>), reserved_username: Option<Username>

The signing payload is (account, verifier, identifier_key, username_prefix, reserved_username).encode() where verifier is the attester (origin of the attest call)