[feature]: Support reconciliation on metadata (annotation) is changed

[pantosha]

Is your feature request related to a problem? Please describe.

Our operator reacts to annotation changes in custom resources.
In the current implementation ReconcileAsync() is not called when only .metadata is changed:

https://github.com/buehler/dotnet-operator-sdk/blob/de986bf8dc9548bfeaccdd2fbe6cb174c302fe5f/src/KubeOps.Operator/Watcher/ResourceWatcher%7BTEntity%7D.cs#L246-L254

Reason is

The .metadata.generation value is incremented for all changes, except for changes to .metadata or .status.

https://kubernetes.io/docs/tasks/extend-kubernetes/custom-resources/custom-resource-definitions/#status-subresource

Describe the solution you would like

Any solution that allows reacting on metadata changes:

• always call ReconcileAsync() when metadata is changed
• provide an option to override behavior when ReconcileAsync() is called
• add overload or new method that will be called to .metadata or .status changes

Additional Context

Similar issue #668

Now we are testing a workaround when .generation is reset during serialization using IJsonOnDeserialized:

public partial class V1CustomResource : CustomKubernetesEntity<V1V1CustomResource .EntitySpec>, IJsonOnDeserialized
{
    // ...
    public void OnDeserialized()
    {
        // HACK
        if (Metadata.Annotations?.ContainsKey("special-annotation") == true)
        {
            Metadata.Generation = null;
        }
    }
}