It computes SHA256 hash of the specified file and then signs the hash
with the key that corresponds to the given credentialId. The result is
DER encoded ECDSA signature which is saved to ".sig".
maybe add an extra command in here for literally just passing 32 bytes (in hex, base64 or whatever) and pass these to the sign function
as the command in the fw is already equipped to precisely do that
It has the following syntax: solo key sign-file
It computes SHA256 hash of the specified file and then signs the hash with the key that corresponds to the given credentialId. The result is DER encoded ECDSA signature which is saved to ".sig".