Problem: our sample contracts are a bit old, they have things
that are removed in Babylon and don't have new Babylon's things.
We want to sync them with upstream from time to time and we didn't
do it for a long time.

Solution: take tests from
https://gitlab.com/tezos/tezos/tree/ccaad09cbc776f84b4ca004ef03f0793d1c4ac51/src/bin_client/test/contracts
except for deprecated ones. It's latest `zeronet` branch.
Some contracts are temporary skipped in our code because they require
some issues that are not resolved yet.