feat: struct support

[antazoey]

Environment information

When interacting with a contract that accepts structs as inputs, I am unable to properly provide the values

What went wrong?

An example: use acc.transfer().. The result us a Uint256 struct. The failure causes transfer() (and normal contract methods) to not work.

How can it be fixed?

something something Starknet(EcosystemAPI).decode_calldata()

[antazoey]

Note: it seems like dicts work for structs! So this issue might not be an issue anymore :)
But will keep open until we added tests

Edit: issue updated to reflect that we just need tests