[REQ] Dedicated go generator library for kubernetes

the kubernetes community is enhancing its integration w/ the openapi-specs for CRD. there will be more and more users thinking about generating codes for kubernetes-related development usages while the current generic go generator doesn't generate out-of-box models fits into kubernetes SDK. e.g.

model_foo.go

// +k8s:deepcopy-gen:interfaces=k8s.io/apimachinery/pkg/runtime.Object
type Foo struct {
    // APIVersion defines the versioned schema of this representation of an object. Servers should convert recognized schemas to the latest internal value, and may reject unrecognized values. More info: https://git.k8s.io/community/contributors/devel/api-conventions.md#resources
    ApiVersion string `json:"apiVersion,omitempty"`
    // Kind is a string value representing the REST resource this object represents. Servers may infer this from the endpoint the client submits requests to. Cannot be updated. In CamelCase. More info: https://git.k8s.io/community/contributors/devel/api-conventions.md#types-kinds
    Kind     string                             `json:"kind,omitempty"`
    Metadata v1.ObjectMeta                      `json:"metadata,omitempty"`
    Spec     FooSpec `json:"spec,omitempty"`
}

func (o *Foo) GetObjectKind() schema.ObjectKind {
    return &v1.TypeMeta{o.Kind, o.ApiVersion}
}

func (o *Foo) GetObjectMeta() v1.Object {
    return &o.Metadata
}

register.go:

var (
	SchemeBuilder = runtime.NewSchemeBuilder(
		addKnownTypes,
	)
	AddToScheme = SchemeBuilder.AddToScheme
)

func addKnownTypes(scheme *runtime.Scheme) error {
	metav1.AddToGroupVersion(scheme, schema.GroupVersion{"example.io", "v1alpha1"})
	scheme.AddKnownTypeWithName(schema.GroupVersionKind{"example.io", "v1alpha1", "Foo"},
		&Foo{},
	)
	return nil
}

basically, there're following things we need to add to the code template:

1. comment tags on the model: // +k8s:deepcopy-gen:interfaces=k8s.io/apimachinery/pkg/runtime.Object
2. extension methods: GetObjectKind, GetObjectMeta
3. additional imports for kubernetes depedencies
4. rendering register.go for installing models

/cc @wing328

Start with the existing generic Go generator and compare its model template with the model_foo.go example in the issue; then trace how register.go would be rendered. Done means a dedicated Kubernetes generator produces the requested model tags, extension methods, dependency imports, and registration file.