Explicit pattern match on all ledger certificates constructors. Remove redundant module

[carbolymer]

Changelog

- description: |
    Explicit pattern match on all ledger certificates constructors.
    Remove `getIsCardanoEraConstraint`. Use `cardanoEraConstraints` instead.

# uncomment types applicable to the change:
  type:
  # - feature        # introduces a new feature
   - breaking       # the API has changed in a breaking way
  # - compatible     # the API has changed but is non-breaking
  # - optimisation   # measurable performance improvements
   - improvement    # QoL changes e.g. refactoring
  # - bugfix         # fixes a defect
  # - test           # fixes/modifies tests
  # - maintenance    # not directly related to the code
  # - release        # related to a new release preparation
  # - documentation  # change in code docs, haddocks...

Context

https://github.com/input-output-hk/cardano-api/pull/268/files#r1337354463

Checklist

• Commit sequence broadly makes sense and commits have useful messages
• The change log section in the PR description has been filled in
• New tests are added if needed and existing tests are updated. These may include:
  • golden tests
  • property tests
  • round trip tests
  • integration tests
    See Running tests for more details
• 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
• The changelog section in the PR is updated to describe the change
• Self-reviewed the diff

[smelc]

I didn't get the details but it does look really equivalent to the state before this PR

[Jimbo4350]

DelegStakeTxCert has a stake credential. We should put TODOs by certificates that contain stake pool credentials while we think about what to do with the StakeCredential type.

[Jimbo4350]

RegTxCert, RegDepositTxCert, UnRegDepositTxCert have stake credentials

[carbolymer]

The function is used here to retrieve all deregistration certificates (this could be one function instead of two though). I specifically didn't want to change the behaviour.

The question is, is the current behaviour correct, or should we fetch all certificates instead?

[carbolymer]

@smelc yes, that is the point of this PR. I was addressing a remark from a different PR.