DRep deposits test

[palas]

Description

This PR addresses: #5601
For that it:

• Adds two test scenarios where a DRep tries to register from scratch:
  • One where a deposit is enough
  • One where deposit is not enough
• Then it tests whether the deposit that is enough got recorded in the ledger state by using foldEpochState
• For reusing as much code as possible it also exposes and uses the internal function checkDRepsNumber' but renamed as something more meaningful and precise: getDRepInfo

Fixes #5742

Checklist

• Commit sequence broadly makes sense and commits have useful messages
• New tests are added if needed and existing tests are updated. These may include:
  • golden tests
  • property tests
  • roundtrip tests
  • integration tests
    See Runnings tests for more details
• Any changes are noted in the CHANGELOG.md for affected package
• The version bounds in .cabal files are updated
• CI passes. See note on CI. The following CI checks are required:
  • Code is linted with hlint. See .github/workflows/check-hlint.yml to get the hlint version
  • Code is formatted with stylish-haskell. See .github/workflows/stylish-haskell.yml to get the stylish-haskell version
  • Code builds on Linux, MacOS and Windows for ghc-8.10.7 and ghc-9.2.7
• Self-reviewed the diff

[smelc]

Good stuff 👍

[Jimbo4350]

LGTM! Some minor comments about where code should live but I wouldn't block the PR on this.