Adds better support for app_plugins loading assets in a safer way and without having to pass refs

src/Umbraco.Web.UI.NetCore/Program.cs

@@ -1,5 +1,4 @@
 using Microsoft.AspNetCore.Hosting;
-using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.Hosting;
 using Microsoft.Extensions.Logging;
 
@@ -8,20 +7,18 @@ namespace Umbraco.Cms.Web.UI.NetCore
     public class Program
     {
         public static void Main(string[] args)
-            => CreateHostBuilder(args)
+        {
+            CreateHostBuilder(args)
                 .Build()
                 .Run();
+        }
 
         public static IHostBuilder CreateHostBuilder(string[] args) =>
             Host.CreateDefaultBuilder(args)
-#if DEBUG
-                .ConfigureAppConfiguration(config
-                    => config.AddJsonFile(
-                            "appsettings.Local.json",
-                            optional: true,
-                            reloadOnChange: true))
-#endif
-                .ConfigureLogging(x => x.ClearProviders())
-                .ConfigureWebHostDefaults(webBuilder => webBuilder.UseStartup<Startup>());
+                .ConfigureLogging(x =>
+                {
+                    x.ClearProviders();
+                })
+                .ConfigureWebHostDefaults(webBuilder => { webBuilder.UseStartup<Startup>(); });
     }
 }

src/Umbraco.Web.UI.NetCore/Startup.cs

@@ -45,7 +45,7 @@ namespace Umbraco.Cms.Web.UI.NetCore
         {
 #pragma warning disable IDE0022 // Use expression body for methods
             services.AddUmbraco(_env, _config)
-                .AddBackOffice(_env)
+                .AddBackOffice()
                 .AddBackOfficeExternalLogins(logins =>
                 {
                     var loginProviderOptions = new BackOfficeExternalLoginProviderOptions(