Add extra StepDefinitionPatternType for other than original gherkin realizations

[elchupanebrej]

🤔 What's the problem you're trying to solve?

As a developer of https://github.com/elchupanebrej/pytest-bdd-ng I try to implement messages protocol. pytest-bdd-ng have extra step definition patterns supported, so it can't fire correct messages

✨ What's your proposed solution?

Add extra type to define non-original step definition patterns; Make it non-required

messages/jsonschema/StepDefinition.json

Line 18 in 5b02bdc

"CUCUMBER_EXPRESSION",

[mpkorstanje]

With somewhat recent events in mind I don't think we'll get a working consensus on this anytime soon.

In the short term would not emitting the StepDefinition message when the pattern is neither regex nor cucumber expression work for you?