Aptos transaction fee

Aptos native transfer fee is $0.0000391 (p50, 24h). Aptos charges gas used times the gas unit price in octas; an `aptos_account::transfer` of APT to an account that already exists burns 62 to 66 gas units (measured on mainnet), and the fullnode publishes deprioritized, standard and prioritized unit prices that map to the slow, standard and fast tiers. A transfer that creates the recipient account also pays its storage and costs far more; that case is out of scope. Computed via `estimate_gas_price` times 63 gas units times live APT price.