* Fix image name parsing with name and digest
Image names may contain both tag name and digest. For example
`nginx:1.21.5@sha256:7826426c9d8d310c62fc68bcd5e8dde70cb39d4fbbd30eda3b1bd03e35fbde29`. Kustomizations with image transforms will not match
these image because the image parser assumes either a tag or digest, but not
both.
For a real life example of kuberenetes deployments that might need to perform
these types of transforms is from the [tekton-pipelines](https://github.com/tektoncd/pipeline) project (see the release.yaml).
* Return digest property from image name parser
image.Split now returns 3 fields: name, tag, and digest. The tag and digest
fields no longer include their respective delimiters (`:` and `@`).
* Fix merge file indentation
* Refactor imagetag updater string builder
