Backport ShowUnroutableContentWarnings to V13 (#18479)

Author: kjac

src/Umbraco.Core/Configuration/Models/ContentSettings.cs

@@ -160,6 +160,7 @@ @keyframes umbraco-preview-badge--effect {{
     internal const bool StaticDisableUnpublishWhenReferenced = false;
     internal const bool StaticAllowEditInvariantFromNonDefault = false;
     internal const bool StaticShowDomainWarnings = true;
+    internal const bool StaticShowUnroutableContentWarnings = true;
 
     /// <summary>
     ///     Gets or sets a value for the content notification settings.
@@ -285,4 +286,10 @@ @keyframes umbraco-preview-badge--effect {{
     /// </summary>
     [DefaultValue(StaticShowDomainWarnings)]
     public bool ShowDomainWarnings { get; set; } = StaticShowDomainWarnings;
+
+    /// <summary>
+    /// Gets or sets a value indicating whether to show unroutable content warnings.
+    /// </summary>
+    [DefaultValue(StaticShowUnroutableContentWarnings)]
+    public bool ShowUnroutableContentWarnings { get; set; } = StaticShowUnroutableContentWarnings;
 }

src/Umbraco.Web.BackOffice/Controllers/ContentController.cs

@@ -1278,6 +1278,11 @@ private void AddPublishRoutableErrorNotifications(
         SimpleNotificationModel globalNotifications,
         string[]? successfulCultures)
     {
+        if (_contentSettings.ShowUnroutableContentWarnings is false)
+        {
+            return;
+        }
+
         IContent? content = publishStatus.FirstOrDefault()?.Content;
         if (content is null)
         {