feat: saved api_key to keychain for user

[lifeizhou-ap]

This is a draft PR only for early feedback. It does not have test yet and also depends on the exchange PR

What When the api key environment variable does not exist,

• it looks up the api key from keychain. if it does not exist, then
• the users are prompted to enter the api key and
• the users are prompted whether they want to save the api key in the keychain

)

[lamchau]

very cool! how would a user update the keychain with the same prompts (typo, rotation, etc)?

just had a thought! what do you think of a goose config (and maybe even a goose check)? that way we can use it as a catch all to do things

• check latest version
• check profiles
• check api keys of each providers (both environment variables and keychain)?