Consistent naming for stake-pool command related types, functions and modules

[newhoggy]

Changelog

- description: |
    Consistent naming for `stake-pool` command related types, functions and modules
# 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

There are inconsistencies in the naming of type functions and modules related to the stake-pool commands. Sometimes, the word "stake" is omitted, sometimes not. Sometimes the word "Cert" is used instead of "Certificate". Sometimes the "Cmd" suffix is used and sometimes not. And so forth.

This PR renames all these things to follow exactly how the command it implements is named.

This PR also drops Shelley prefix for such names because everything is basically in the Shelley based era, so the distinction isn't necessary.

No CLI commands API changes are introduced in this PR.

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