Make notification service able to handle segmented content

[kjac]

Prerequisites

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

If there's an existing issue for this PR then this fixes #20045

Description

See the linked issue for a description.

Testing this PR

You'll need to be able to receive notification emails from Umbraco. An easy way to do that is to configure the SMTP options to use the SpecifiedPickupDirectory in appsettings.json:

{
  "Umbraco": {
    "CMS": {
      "Global": {
        "Smtp": {
          "From": "your@email.here",
          "DeliveryMethod": "SpecifiedPickupDirectory",
          "PickupDirectoryLocation": "C:\\Temp\\MailDrop"
        }
      },
      ....

You'll also need to enable segments for document types. This code snippet should do the trick in V13:

using Umbraco.Cms.Core.Composing;
using Umbraco.Cms.Core.Events;
using Umbraco.Cms.Core.Notifications;

namespace Umbraco.Cms.Web.UI.Custom;

public class ServerVariablesParsingNotificationHandler : INotificationHandler<ServerVariablesParsingNotification>
{
    public void Handle(ServerVariablesParsingNotification notification)
    {
        if (!notification.ServerVariables.TryGetValue("umbracoSettings", out var umbracoSettingsObject)
            || umbracoSettingsObject is not IDictionary<string, object> umbracoSettings)
        {
            umbracoSettings = new Dictionary<string, object>();
            notification.ServerVariables.Add("umbracoSettings", umbracoSettings);
        }

        umbracoSettings["showAllowSegmentationForDocumentTypes"] = true;
    }
}

public class EnableSegmentsComposer : IComposer
{
    public void Compose(IUmbracoBuilder builder)
        => builder.AddNotificationHandler<ServerVariablesParsingNotification, ServerVariablesParsingNotificationHandler>();
}

With all that in place, create a new doctype with "Allow segmentation" enabled:

Note that you don't actually need any segmented properties to test this PR 😄

Now create a document of the segmented doctype, and sign up for any notification for that document. I've used the "Update" notification for testing, because it's easy to trigger.

When this is in place, trigger the notification (e.g. save the document again if you're using the "Update" notifcation).

Without this PR, the NotSupportedException from NotificationService bubbles all the way into the UI:

With this PR, the notification email should be sent (or generated on disk, if you configured SpecifiedPickupDirectory).

[AndyButland]

Tests out as described. I've verified with an invariant, vary by culture and vary by segments configured document type and see the emails coming through with expected content in all cases.

[AndyButland]

🍒 picked for 16.3 in 546849d