rishflab e42812ba37 Add subcommand to print internal bitcoin wallet descriptor
Example:

 cargo run --package swap --bin swap -- export-bitcoin-wallet

{"descriptor":"wpkh(xprv9s21ZrQH143K2q85eUf2ppCtti2Zar6aDCW5dCC5DG9VvutJ3cpe3Qf9wZpQeraNf9JEuGem1RyJZQMEWCN2DpWyL5WbsvmSW6wbL7Jq53H/84'/0'/0'/0/*)","blockheight":0,"label":"cli-bitcoin"}
2021-10-07 11:22:04 +11:00
..
2021-10-07 09:52:26 +11:00