This update removes multi-share generation. Simplifies the derivation path. Truncates entropy rather than reading the DRNG.

Generates codex32 secrets

• The threshold and identifier are ignored for derivation here and only cosmetically affect the string if specified
• Default threshold = "0" and identifer as Bech32-encoded BIP32 fingerprint of the master seed
  Generates loose codex32 shares
• Only the first threshold share indices can be generated
• The threshold and identifier MUST be specified as they affect the derivation.
• The 20-LSB of the bip85 {index} is set to the chosen codex32 identifier so different share sets (unique identifier) have unique payloads.

This supports more use-cases than the original design and is a fraction of the original length.

I appreciate any reviews.