Add (un)publishing details to TreeChange notifications

[kjac]

Prerequisites

• I have added steps to test this contribution in the description below

Description

This PR adds additional (un)publishing info to TreeChange (specifically which cultures were affected by the operation), to be consumed by ContentTreeChangeNotification handlers.

This additional info is also added to the ContentCacheRefresherNotification, to make it available in a load balanced scenario.

For invariant content, the wildcard (*) is used to communicate the affected cultures.

Testing this PR

Add a notification handler to ContentTreeChangeNotification and ContentCacheRefresherNotification, and verify that the PublishedCultures and UnpublishedCultures properties match any (un)publishing operations performed in the backoffice.

Here's a notification handler 😄

using Umbraco.Cms.Core.Cache;
using Umbraco.Cms.Core.Composing;
using Umbraco.Cms.Core.Events;
using Umbraco.Cms.Core.Models;
using Umbraco.Cms.Core.Notifications;
using Umbraco.Cms.Core.Services.Changes;

namespace Umbraco.Cms.Web.UI.Custom;

public class ContentCacheRefresherNotificationHandler :
    INotificationHandler<ContentCacheRefresherNotification>,
    INotificationHandler<ContentTreeChangeNotification>
{
    public void Handle(ContentCacheRefresherNotification notification)
    {
        if (notification.MessageObject is not ContentCacheRefresher.JsonPayload[] payloads)
        {
            return;
        }

        foreach (ContentCacheRefresher.JsonPayload payload in payloads)
        {
            Console.WriteLine(
                "## Content cache refresher - published = {0}, unpublished = {1}",
                string.Join(", ", payload.PublishedCultures ?? []),
                string.Join(", ", payload.UnpublishedCultures ?? []));
        }
    }

    public void Handle(ContentTreeChangeNotification notification)
    {
        foreach (TreeChange<IContent> change in notification.Changes)
        {
            Console.WriteLine(
                "## Content tree change - published = {0}, unpublished = {1}",
                string.Join(", ", change.PublishedCultures ?? []),
                string.Join(", ", change.UnpublishedCultures ?? []));
        }
    }
}

public class ContentCacheRefresherNotificationHandlerComposer : IComposer
{
    public void Compose(IUmbracoBuilder builder)
        => builder.AddNotificationHandler<ContentCacheRefresherNotification, ContentCacheRefresherNotificationHandler>();
}

[Zeegaan]

Looks good, tests good 🚀

[Zeegaan]

Cherry picked for 13.6 🚀