Support for bc-sskr in addition to SLIP39.
https://github.com/BlockchainCommons/bc-sskr#design-notes
https://github.com/BlockchainCommons/bc-slip39
SLIP-39 does not round trip with BIP-39. For Shamir's Secret Sharing, we have replaced this with the newer bc-sskr library, which has received a full security review and is ready for production deployment.