util: Simplify `unlocks_keyring` and move it (and one more) into `cmds.util`

[xdustinface]

• Drops the unused parameter
• Makes it not longer be a decorator but just a normal function call. Im not sure why making it a decorator would be better here since it just makes hinting complex. Let me know if i miss the point of it.
• Moves it alongside with obtain_current_passphrase into chia.cmds.util since this code is CLI stuff actually.

This is a first step to get rid of CLI code in keychain related parts, there are still places which need to be fixed.