Currently the default xjc task is created and its output is added to the main `SourceSet`. I have a project that only generates code for the test `SourceSet`. Ideally I would like the ability to switch the source set of the generated code. It seems like the main `SourceSet` is being hard-coded to be added to [here](https://github.com/bjornvester/xjc-gradle-plugin/blob/main/src/main/kotlin/com/github/bjornvester/xjc/XjcPlugin.kt#L88-L91)