[java] provide a public method to convert a cucumber expression into parsed segments

For regularExpressions it is already possible to parse them into groups with a [public method](https://github.com/cucumber/cucumber-expressions/blob/c9b57b0eb3649e79c0a57630520f955196abf742/java/src/main/java/io/cucumber/cucumberexpressions/Group.java#L58), a similar approach should be possible for the CucumberExpressionsParser as well (maybe the Groups Aproach could be reused here...)