[Feature]: User can delete an env var by setting it to null in the manifest

[matt-royal]

Blockers/Dependencies

No response

Background

As a korifi user
I want to be able to delete environment variables via the manifest
So that I can use the same manifest as with cf-for-vms

Acceptance Criteria

GIVEN an application named "node" that has the environment variable test set to value (via manifest or via cf set-env)
WHEN I re-push the same app using a manifest that sets test to nil (see below)
AND I run cf env node
THEN I should see that there is no environment variable called test in the response

---

Here's an example manifest to clear the test env var:

applications:
  - name: node
    env:
      test: ~

Dev Notes

This will require several changes:

• The field type for env will need to support nil values
• The nil value will need to be passed through to AppRepo.CreateOrPatchAppEnvVars()
• AppRepo.CreateOrPatchAppEnvVars() will need to delete any environment variable that was set to nil

[matt-royal]

Based on this conversation, I think that this feature is broken in tas-for-vms also, so this isn't a priority.