lock transaction should use a high priority feerate

[delta1]

From what I recall, the lock transaction fee is set as low as possible, which during high fee environments means that it may take too long too confirm. The swap tool times out after 2 hours on mainnet waiting for the lock tx to confirm.

Originally posted by @delta1 in #1563 (reply in thread)

[delta1]

looks like estimate_fee uses 3 block target for mainnet, so maybe a first step is putting in some logging for the estimated feerate

https://github.com/comit-network/xmr-btc-swap/blob/master/swap/src/cli/command.rs#L22

[jadsilva]

bitcoin redeem transactions are also lasting forever