Requirement for the code to compile necessitates manual intervention during codegen

### What problem are you facing?

When you use a custom resource type in a file under `apis/group/version` to do the following:
```
func (mg xpresource.Managed) {
cr, ok := mg.(*Cluster)
}
```
It expects that `*Cluster` satisfies `xpresoruce.Managed` interface but in order to do that angryjet needs to work to generate those functions. To get out of the chicken-egg problem, we end up commenting out the code, run agryjet, and enable it again.

### How could Crossplane help solve your problem?

If it's possible, we could disable the expectation that the package should be compile-able. One option could be to give individual files, maybe?