Implement directory structure ADR changes

[foot]

ADR https://github.com/weaveworks/weave-gitops-private/blob/main/docs/adrs/0007-directory-layout.md

What changes to make?

• Create / delete cluster PR should target .weave-gitops/apps/capi/$clustername.yaml
• gitops upgrade command: wge helmprofile should be installed into .weave-gitops/clusters/management/user/wge-HelmProfile.yaml
• docs should recommend adding templates to ?
  • .weave-gitops/clusters/management/user/capi-templates/capd-template.yaml
• ?

[foot]

@kevin does this seem okay still?