Maintenance page when in upgrade state (#13551)

* Added functionality to show maintenance page and fixed issues with showing custom api controllers and 404 page, when umbraco had been in install or upgrade state

* Fixed Tests

* Fixed typo

* Fixed issue with login screen redirecting to website when in upgrade state, instead of backoffice

src/Umbraco.Web.Common/Controllers/MaintenanceModeActionFilterAttribute.cs

@@ -0,0 +1,42 @@
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.AspNetCore.Mvc.Filters;
+using Microsoft.Extensions.Options;
+using Umbraco.Cms.Core;
+using Umbraco.Cms.Core.Configuration.Models;
+using Umbraco.Cms.Core.Services;
+using Umbraco.Cms.Web.Common.ActionsResults;
+
+namespace Umbraco.Cms.Web.Common.Controllers;
+
+internal sealed class MaintenanceModeActionFilterAttribute : TypeFilterAttribute
+{
+    public MaintenanceModeActionFilterAttribute() : base(typeof(MaintenanceModeActionFilter))
+    {
+    }
+
+    private sealed class MaintenanceModeActionFilter : IActionFilter
+    {
+        private readonly IRuntimeState _runtimeState;
+        private readonly IOptionsMonitor<GlobalSettings> _globalSettings;
+
+        public MaintenanceModeActionFilter(IRuntimeState runtimeState, IOptionsMonitor<GlobalSettings> globalSettings)
+        {
+            _runtimeState = runtimeState;
+            _globalSettings = globalSettings;
+        }
+
+        public void OnActionExecuting(ActionExecutingContext context)
+        {
+            if (_runtimeState.Level == RuntimeLevel.Upgrade && _globalSettings.CurrentValue.ShowMaintenancePageWhenInUpgradeState)
+            {
+                context.Result = new MaintenanceResult();
+            }
+
+        }
+
+        public void OnActionExecuted(ActionExecutedContext context)
+        {
+
+        }
+    }
+}

src/Umbraco.Web.Common/Controllers/RenderController.cs

@@ -16,6 +16,7 @@ namespace Umbraco.Cms.Web.Common.Controllers;
 /// </summary>
 [ModelBindingException]
 [PublishedRequestFilter]
+[MaintenanceModeActionFilter]
 public class RenderController : UmbracoPageController, IRenderController
 {
     private readonly ILogger<RenderController> _logger;