[Chore]: Make cf-k8s-controllers KpackImageTag and PackageRegistryBase tolerant to trailing slashes

[Birdrock]

Background

Current, KpackImageTag and PackageRegistryBase must be specified without a trailing slash. It should be tolerant to these specified with or without a trailing slash.

Action to take

Add toleration for trailing slashes.

Impact

Medium impact, as it will mitigate potential configuration issues. Small effort to resolve.

Dev Notes

The relevant code snippets are here:

• https://github.com/cloudfoundry/cf-k8s-controllers/blob/9a978623c7153f7b7575f2269438926b1b3174fe/api/apis/package_handler.go#L213
• https://github.com/cloudfoundry/cf-k8s-controllers/blob/9a978623c7153f7b7575f2269438926b1b3174fe/controllers/controllers/workloads/cfbuild_controller.go#L203
• Could handle via the config struct or with ytt template validation, etc- up to implementor

[Birdrock]

Resolved with #318