Support package-info.java for spotless licenser

[Machine-Maker]

Spotless ignores package-info.java and module-info.java files. There are some workarounds found in this issue. But it doesn't seem possible to integrate them with indra's custom header supplier logic, as the createHeaderSupplier method is in the extension impl.

Indra should include options to include package-info by the workaround found in that issue, or at least make it possible for users of the plugin to implement it while retaining the other header qol configs indra adds.