CRD-Generator v2: Gradle Plugin

[baloo42]

Is your enhancement related to a problem? Please describe

Because the CRD-Generator annotation processor is now deprecated, we need a replacement.
(see #5942)

Describe the solution you'd like

A CRD-Generator gradle plugin could search for a top level annotation (or interface) and generate the CRDs using the CRD-Generator api.

Describe alternatives you've considered

No response

Additional context

• Jandex could be used to find and index the relevant annotations/classes.
• The following options should be supported:
  • Enable / disable parallel generation
  • CRD versions (v1, v1beta1)
    (TBD: There are thoughts to drop v1beta1 which makes this option irrelevant)
  • outputPath
  • header in output files
  • Allow to add additional labels
  • Allow to add additional annotations
  • Enable debug output

The also planned CRD-Generator maven plugin (#5944) should support the same options.

[shawkins]

As suggested by @manusa we can just start with a clone of https://github.com/fabric8io/kubernetes-client/tree/main/java-generator/gradle-plugin