WIP: [TBTC-29] Generic multisig contract

Description

We have generic multisig contract which is used in some of our projects in order to support multisig operations. However, it always fails using FAILWITH () (sometimes inside macro), which complicates work with this contract. So it will be more convenient to fail with some more human-readable messages. In order to achieve this, the whole contract was rewritten in Lorentz and custom errors were added.

Related issue(s)

https://issues.serokell.io/issue/TBTC-29

✅ Checklist for your Merge Request

Related changes (conditional)

• Tests (see short guidelines)

  • If I added new functionality, I added tests covering it.
  • If I fixed a bug, I added a regression test to prevent the bug from silently reappearing again.

• Documentation

  • I checked whether I should update the docs and did so if necessary:
    • README
    • Haddock
    • docs/

Stylistic guide (mandatory)

• My commits comply with the following policy.
• My code complies with the style guide.