feat: support heap types return from scripts

[iqdecay]

#848 introduced Vec<> type return from contracts, the same should be done for scripts.
#868 introduced Bytes type return from contracts, the same should be done for scripts.

[iqdecay]

This is currently blocked because returning heap-type data from contract calls is possible only because we are injecting additional bytecode in the script that calls the contract. Since in script calls there is no "calling script", this is not currently possible. We need support for heap types from the compiler.

[Dhaiwat10]

@iqdecay we need to implement this on the TS SDK, too. Can you pls share any issues that you are tracking on the compiler so that we know when the support is there?

[iqdecay]

There currently isn't any issue to track for Sway unfortunately.

[hal3e]

done in: #1303