Return data from executed transactions

[miloszm]

Summary

Currently, after executing transactions, we do not have return data which results from transaction's execution. In particular, in case of contract deployment transaction, we do not have information about deployment contract id, and no deployment specific error information, should transaction be successful yet deployment was not done, for example in case of contract-already-exists error.

Possible solution design or implementation

Devise a scheme to pass the return data back to transaction executor. Possibly, enrich the SpentTransaction struct with a field carrying the return data.

Additional context

This issue is related to the deployment epic #1071, yet it is also wider in scope, as it pertains to transactions in general.