new command kustomize edit add buildmetadata

[natasha41575]

This is the last PR needed to finish implementation of the proposal to add origin and transformer annotations [link to KEP].

This adds a command kustomize edit add buildmetadata that allows users to edit the buildMetadata options in the kustomization file. It also adds kustomize edit set buildmetadata and kustomize edit remove buildmetadata commands.

E.g. kustomize edit add buildmetadata managedByLabel, kustomize edit add buildmetadata originAnnotations,transformerAnnotations

/cc @yuwenma
/cc @KnVerey

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[yuwenma]

Shall we add the "buildmetadata" to kustomize edit remove as well?

[natasha41575]

Shall we add the "buildmetadata" to kustomize edit remove as well?

Yes we should, I was thinking about doing that in a separate PR but I can add it to this one instead

[yuwenma]

Normally we define the function Validate to be sharable among setBuildMetadataOptions, addBuildMetadataOptions, removeBuildMetadataOptions? But I can see this may introduces more code structure to kustomize/commands/set dir. So it defers to you

What we can do to share the code: add a new structure buildMetadataValidator which has the Validate func, and itself is an attribute to the other functions? e.g.

package cmdvalidate // a sub dir under kustomize/commands/internal
type buildMetadataValidator struct {}

func (b *buildMetadataValidator) Validate() {
   ...
}

type setBuildMetadataOptions struct {
       *buildMetadataValidator
	buildMetadataOptions []string
}

[natasha41575]

I did this in kustomize/commands/util/validate.go, because the util package already had some common functions shared among the edit commands. Thanks for the suggestion!

[yuwenma]

/lgtm

Looks great!