476: change-rule to delete packageInstall/app before service account and RBAC

[kumaritanushree]

What this PR does / why we need it:

This PR has change-rule added in default.go to delete packageInstall/app (kctrl App CR) before service account and RBAC

Which issue(s) this PR fixes:

Fixes #476

Does this PR introduce a user-facing change?

NONE

Additional Notes for your reviewer:

Review Checklist:

• Follows the developer guidelines
• Relevant tests are added or updated
• Relevant docs in this repo added or updated
• Relevant carvel.dev docs added or updated in a separate PR and there's
  a link to that PR
• Code is at least as readable and maintainable as it was before this
  change

Additional documentation e.g., Proposal, usage docs, etc.:

[kumaritanushree]

With these changes ordering of upsert and deletion of resources packageInstall/App, service account and RBAC will be:

Upsert: (There is no change in upsert rule, already working as per requirement with the existing rules)

Changes are sorted in order that they will be applied. They will be applied in parallel within their group. Each change lists other changes that it will wait for before being applied.

1. 
     1. (upsert) serviceaccount/default-ns-sa (v1) namespace: default (0)
     2. (upsert) role/default-ns-role (rbac.authorization.k8s.io/v1) namespace: default (0)
     3. (upsert) secret/pkg-demo-values (v1) namespace: default (0)
2.
     1. (upsert) rolebinding/default-ns-role-binding (rbac.authorization.k8s.io/v1) namespace: default (+1) ^
3.
     1. (upsert) app/simple-app-cr (kappctrl.k14s.io/v1alpha1) namespace: default (+4) ^
     2. (upsert) packageinstall/pkg-demo (packaging.carvel.dev/v1alpha1) namespace: default (+4) ^

Delete:

Changes are sorted in order that they will be applied. They will be applied in parallel within their group. Each change lists other changes that it will wait for before being applied.

1. 
    1. (delete) packageinstall/pkg-demo (packaging.carvel.dev/v1alpha1) namespace: default (0)
    2. (delete) app/simple-app-cr (kappctrl.k14s.io/v1alpha1) namespace: default (0)
    3. (delete) secret/pkg-demo-values (v1) namespace: default (0)
2.
    1. (delete) role/default-ns-role (rbac.authorization.k8s.io/v1) namespace: default (+1) ^
    2. (delete) rolebinding/default-ns-role-binding (rbac.authorization.k8s.io/v1) namespace: default (+1) ^
    3. (delete) serviceaccount/default-ns-sa (v1) namespace: default (+1) ^        4. 

[praveenrewar]

Looking pretty good now.

[cppforlife]

change-groups.kapp.k14s.io/packageinstall => change-groups.kapp.k14s.io/kapp-controller-packageinstall

[praveenrewar]

LGTM!