Function cuprate_blockchain::service::init_read_service_with_pool

pub fn init_read_service_with_pool(
    env: Arc<ConcreteEnv>,
    pool: Arc<ThreadPool>,
) -> BlockchainReadHandle

Initialize the blockchain database read service, with a specific rayon thread-pool instead of creating a new one.

Should be called once per actual database, although nothing bad will happen, cloning the BlockchainReadHandle is the correct way to get multiple handles to the database.