Allow configurable apis/ folder structure to avoid path collisions

[BigGold1310]

What problem are you facing?

Generating APIs from an XRD or simple schema can conflict when two resources share the same kind but belong to different API groups. For example:

kubernetesclusters.onprem.example.com
kubernetesclusters.cloud.example.com

Both of these generate today into the same directory, apis/kubernetesclusters/, causing a conflict.

There is currently an option to specify the output path explicitly, but that doesn't scale for larger repositories or automated build tooling, where paths need to be derived consistently rather than set by hand.

How could Crossplane help solve your problem?

Allow conflict-free generation of XRD definitions from an XR or simple schema. Ideas:

1. Add an option in crossplane-project.yaml to configure how the apis/ folder is populated, using a template string such as {{ groupElement[1] }}/{{ kindPlural }}. For example, this would resolve to:

apis/
  onprem/
    kubernetesclusters/
      definition.yaml
  cloud/
    kubernetesclusters/
      definition.yaml

2. Default to a non-conflicting structure, similar to what schemas/ already uses.

[adamwg]

I think I would lean toward solution (2), using a conflict-avoiding layout by default. Given that this only affects generate, it shouldn't be a breaking change - crossplane project build looks through all of apis/, so it will find everything correctly in either the old or new layout.