feat: nested manifests in object transforms

[sdowell]

This change adds support for applying object transforms to nested manifests. The nested manifest pattern is a pattern in which an object has a string field which consists of its own yaml manifest.

As an example, a ConfigMap may contain a manifest bundle in one of its data fields.

A nested manifest will recurse and apply all object transforms to the underlying objects and then write the result back to the parent object.

[k8s-ci-robot]

Hi @sdowell. Thanks for your PR.

I'm waiting for a kubernetes-sigs member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

I understand the commands that are listed here.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.

[sdowell]

/assign @justinsb

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: sdowell
Once this PR has been reviewed and has the lgtm label, please ask for approval from justinsb. For more information see the Kubernetes Code Review Process.

The full list of commands accepted by this bot can be found here.

Needs approval from an approver in each of these files:

• OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment