Show secrets in wallet

[gak]

Right now there's no way of seeing a wallet's phrase or private key via the CLI. The private key is visible via the wallet file, but not the phrase--it uses an Entropy rather than saving the words.

It would be good to have a command, e.g.:

> feeless wallet secret --id

The output would vary depending on the wallet type:

> feeless wallet secret --id xxx # phrase, must match language and word count (1)
west false peanut clarify ready argue stereo pen provide minor shop village behind south day syrup scale abandon arch cook borrow celery tomato disorder

> feeless wallet secret --id xxx # seed
A2DFF190C1310862D6B0997C7FEECE19279A2EF257B2C7E0859167AA2C87F599

> feeless wallet secret --id xxx # private
61E0E1DEFB3FEDC673C58B3CE904B28B93566CA864FD57D566ED12E3C8F4A15A

¹ As part of this change, the word count might need to be added?

• wallet secret command accepting id argument
• phrase
  • ensure the correct word count is shown
• seed
• private