Return `Result` in `stark_sign_message` and `ecdsa_sign_message` cheatcodes

[Draggu]

Which components does the task require to be changed? (think hard pls)

snforge

Description

cheatcode::<'stark_sign_message'>() and cheatcode::<'ecdsa_sign_message'>() currently panic with 'invalid secret_key' or 'message_hash out of range', we should return Result instead.