Bugfix/cck conformance fix

[luke-hill]

This fixes up an existing bug in the CI and also updates CCK to v16

• Ensure attachments now no longer has redundant hook and blank messages
• Fix up examples-tables to parse and run new scenarios plus fix up extra steps
• Refactor existing cucumber-ruby implementation to now lean on external assets instead of duplicating them (I forgot to fix this up ages ago)
• Renamed local step def files to be snake cased (Of sorts), so they're more conformant to ruby style

Type of change

• Refactoring (improvements to code design or tooling that don't change behaviour)
• Bug fix (non-breaking change which fixes an issue)
• Breaking change (will cause existing functionality to not
  work as expected)

Checklist:

Your PR is ready for review once the following checklist is
complete. You can also add some checks if you want to.

• Tests have been added for any changes to behaviour of the code
• New and existing tests are passing locally and on CI
• bundle exec rubocop reports no offenses
• RDoc comments have been updated
• CHANGELOG.md has been updated