DNM: Adding ability to derive solona address

[micahriggan]

Just wanted to see what it'd take to be able to derive the SOL address from what is already in this lib

I ref'd this blog post for an example of address derivation https://www.abiraja.com/blog/from-seed-phrase-to-solana-address

These docs were useful too https://solanacookbook.com/references/keypairs-and-wallets.html#how-to-generate-a-mnemonic-phrase