More thorough swap HTLC checks

[danimoh]

• HTLC timeouts (timestamps and blocks) should be checked to not be in the past, or occurring in the next minutes. See Check whether HTLC timeout timestamps are in the past keyguard#473.
• Bitcoin HTLC scripts should be checked for whether they match the HTLC contract address we got from Fastspot. See comment in USDC-on-Polygon integration keyguard#465 (comment).
• Make sure that the Hub includes all the checks the Keyguard is doing, because Ledger swaps do not go through the Keyguard.