Generic implementation of CRD upgrade preflight check

[everettraven]

This focuses on creating the initial CRD Upgrade Safety preflight check. This should be a minimal implementation focused on:

• Adding the preflight check to the preflight check registry
• Creating an extensible interface for adding checks to be run against CustomResourceDefinition resources

The work done to resolve this issue will be a foundation that allows for future work to be done in parallel and iteratively add functionality to this preflight check.

If the proposal for adding this functionality to carvel-dev/kapp has been accepted prior to starting this work, all changes should be made against carvel-dev/kapp, otherwise the changes should be made against https://github.com/everettraven/kapp/tree/feature/crd-upgrade-safety-preflight

[everettraven]

Done in carvel-dev/kapp as of carvel-dev/kapp#901 - closing