Add WIF format to make_keychain in the CLI

[hstove]

When you generate a keychain in the CLI, it uses the standard STX derivation path (which starts with m/5757'/...). If you try and use the secret key generated from the CLI in a Bitcoin wallet, you won't be able to access the address generated in the CLI. However, one easy fix is for the CLI to output your WIF Private Key (Wallet Import Format), which is supported by many BTC wallets.

To do so:

• Get the WIF key in keys.ts
  • const wif = child.toWIF();
• Add the WIF key to the result of that function
• Update the typescript return type of that function
• Add a test

[friedger]

You can use stacks-gen as a workaround :-)