Generated packages should define an accessible ARMAPIVersion variable

[matthchr]

Describe the current behavior
Today, we have per-resource ARM API versions, for example:

// +kubebuilder:validation:Enum={"2020-11-01"}
type LoadBalancersSpecApiVersion string

const LoadBalancersSpecApiVersion20201101 = LoadBalancersSpecApiVersion("2020-11-01")

This is used like so:

// ConvertToARM converts from a Kubernetes CRD object to an ARM object
func (loadBalancersSpec *LoadBalancers_Spec) ConvertToARM(name string, resolvedReferences genruntime.ResolvedReferences) (interface{}, error) {
        ...
	result.ApiVersion = LoadBalancersSpecApiVersion20201101
        ...

Describe the improvement
Since our packages are per-API version anyway, I think we can do away with the per-resource APIVersion and instead just use a package global one, maybe called ARMAPIVersion.

Then the tests could also use this via:

network "github.com/Azure/azure-service-operator/hack/generated/_apis/microsoft.network/v1alpha1api20201101"
...

network.ARMAPIVersion

[matthchr]

I think @Porges is changing this now