Implement quick fix for generating step definitions

[aslakhellesoy]

🤔 What's changed?

Add quick fix to generate snippets for undefined step definitions.

TODO:

• Detect what language to use for snippets
  • If the settings specify a preferred language, use that
  • Otherwise, scan the glue path and detect the most used language
  • Otherwise, try to determine the language from the presence of other files (pom.xml, package.json, Gemfile etc)
• Determine what file to add the snippet into
  • Find existing glue files, split camel/underscore into words, choose the file with most words present in "snippet words"
  • Otherwise, most recently edited glue file
  • Otherwise, create a new file directly under the glue glob called step_definitions.${ext} - the template context will have one extra property:
    • moduleWords - e.g. ['foo', 'bar'], which the template can use to add e.g. package foo.bar; at the top
      • In order to compute moduleWords we need to strip away any path prefixes (such as src/test/java before making moduleWords)

⚡️ What's your motivation?

Write step definitions quicker, without having to run Cucumber to see snippets. Also to have snippets added to code automatically.

🏷️ What kind of change is this?

• ⚡ New feature (non-breaking change which adds new behaviour)

♻️ Anything particular you want feedback on?

See related PR: cucumber/language-service#46

📋 Checklist:

• I agree to respect and uphold the Cucumber Community Code of Conduct
• I've changed the behaviour of the code
  • I have added/updated tests to cover my changes.
• My change requires a change to the documentation.
  • I have updated the documentation accordingly.
• Users should know about my change
  • I have added an entry to the "Unreleased" section of the CHANGELOG, linking to this pull request.

---

This text was originally generated from a template, then edited by hand. You can modify the template here.