Modernize CRD change process

[metalcycling]

Current CRD changes to MCAD necessitate updating multiple files where the AppWrapper CRD is specified. This is very cumbersome and prone to errors as one may forget to change some of the files, or a fix in one file is not propagated to the others. There are tools like Operator-SDK or Kubebuilder that streamline this process and would make changing the code much simpler. Modernizing to these build systems would be a much needed update.

[astefanutti]

It should be fixed with #456.