Remove duplicate token matcher Python code

[kieran-ryan]

🤔 What's changed?

Change Python implementation of markdown token matcher to inherit from feature file token matcher.

⚡️ What's your motivation?

• Remove duplicated code - ensuring a source of truth and improved maintainability.
• Add missing entry in manifest for markdown token matcher - added automatically as part of build process when running test suite through tox

Existing test suite remained compatible for the feature file and markdown matchers after the change - including with Python 2.

🏷️ What kind of change is this?

• 🏦 Refactoring/debt/DX (improvement to code design, tooling, documentation etc. without changing behaviour)

♻️ Anything particular you want feedback on?

NA.

📋 Checklist:

• I agree to respect and uphold the Cucumber Community Code of Conduct
• I've changed the behaviour of the code
• Users should know about my change
  • I have added an entry to the "Unreleased" section of the CHANGELOG, linking to this pull request.

[mpkorstanje]

Cheers!