Add ability to output signed extrinsic / encoded call

Instead of submitting an extrinsic we should be able to output the signed extrinsic and the encoded call. This can be useful if you want to submit the extrinsic to some other RPCs manually or want to do some inspection.

• Add --no-submit which skips the submission and prints the extrinsic instead
• Add --print-extrinsic which do the submission but also prints the (signed) extrinsic

These commands should also print the data passed to the extrinsic in addition the encoded extrinsic (input bytes to the contract). #573 exposes this as separate command.