feat: update default templates with default and validation markers

[tenstad]

Processes kubebuilder validation and default markers, and exposes them through the fields Validation and Default. These are displayed in two new struct field columns, and validation is shown in type descriptions.

We could introduce this without updating the default template, so that those who want can start using Default and Validation without affecting existing usage.

WONTFIX

• merging enum markers
  • when both a type and the alias type has enum validation
  • or a field and its type has enum validation
  • the current code does not merge them as in the generated CRD
• support for XValidation marker

Example doc

[cla-checker-service]

💚 CLA has been signed

[mowies]

@tenstad @thbkrkr is there a way to move this forward and into the main release? having markers is great, but having separate fields that are directly available in the templates would be much better.

[tenstad]

@mowies @thbkrkr I have now rebased this PR, so that we can start thinking about how we want to introduce markers in the doc. I'm not sure how to best render defaults and validations yet 🤔 The current draft with two new columns use quite a lot of space.

[michelgb]

Any plans to merge this?

[tenstad]

@thbkrkr @mowies @dashanji @michelgb @RealAnna I have now made a few more tweaks and extended the tests some more.

Suggest we move XValidation and correctly merging enum markers (edgecase) outside the scope of this MR (see WONTFIX in description). This one is therefore ready for review now :)

[thbkrkr]

LGTM

Thanks, @tenstad.

[RealAnna]

looks amazing 🚀 looking forward for the release!