[TM-347] Merge `babylon`

Description

Babylon is almost in mainnet, so we are merging babylon branch into master and stop supporting Athens.

The only conflict I have encountered was caused by the fact that ManagedLedger tests have been split in master and in babylon they were modified due to changed constraint (TM-317).

Apart from that I had to add a couple of customErrClass definitions.

Related issue(s)

https://issues.serokell.io/issue/TM-347

✅ 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.