Always use data transformer unless --calldata is passed

[cptartur]

Currently, in the calldata serialization logic in sncast we only try to use data transformer if --arguments flag is prezent. If not, and no --calldata was provided, an empty vec is used as calldata and the transaction fails after execution attempt.

The logic should be changed, so if no --arguments flag is provided, data transformer is called but with an empty vec. This way instead of provider (starknet) error, the user will be shown a nice, data transformer error.