Add pretty-formatters for Gherkin (for Java)

[jamietanna]

Is your feature request related to a problem? Please describe.

As someone who writes Gherkin feature files, I'd like to be sure my formatting is consistent across contributors to the project - whether editing in an IDE, or a text editor - and that can be automated as part of i.e. a code formatter like Spotless

Describe the solution you'd like

Add a pretty-formatter for Gherkin as a first-class citizen. This would allow taking i.e. a String, returning a String that is formatted according to pre-defined rules, and with indentation that can be specified.

I've recently implemented this in https://gitlab.com/jamietanna/gherkin-formatter and have licensed as MIT purposefully so Cucumber could take it as-is.

Describe alternatives you've considered

We write our own formatter.

[aslakhellesoy]

Duplicate of cucumber/gherkin-utils#4. Also see #1725

[aslakhellesoy]

But your code is really nice! Thanks for the effort :-)

[jamietanna]

Thanks @aslakhellesoy - do you think it's worth me raising a separate PR for importing my implementation?

[laeubi]

@jamietanna this could be really usefull especially for the cucumber-eclipse plugin that currently lacks formatting capabilities.