Move @PicocliScript and Groovy dependenies to separate artifact

Is it possible to extract/move:

```
picocli/groovy/
picocli/groovy/PicocliBaseScript.class
picocli/groovy/PicocliScript.class
picocli/groovy/PicocliScriptASTTransformation.class
```
to a separate JAR artifact, ideally I don't want to pull in Groovy into my app since I don't need it, nor does picocli itself.
