V14: Rename new projects (#15836)

* Rename Web.UI.New back to Web.UI

* Delete new backoffiec folder

* Rename client project

* Add new submodule

* Update template csproj

* Remove more mentions of new

* Add missing views

* Moving up the "Umbraco.Web.UI" proj reference, so that it is the first project listed in solution file (.sln) since it will be selected as startup one in VS by default.

* don't include grid

* Update with section of how to get started with backoffice

* Update .github/BUILD.md

Co-authored-by: Elitsa Marinovska <21998037+elit0451@users.noreply.github.com>

* Add line about white page

---------

Co-authored-by: Elitsa <elm@umbraco.dk>
Co-authored-by: Elitsa Marinovska <21998037+elit0451@users.noreply.github.com>

src/Umbraco.Web.UI/Program.cs

@@ -0,0 +1,30 @@
+WebApplicationBuilder builder = WebApplication.CreateBuilder(args);
+
+builder.CreateUmbracoBuilder()
+    .AddBackOffice()
+    .AddWebsite()
+    .AddDeliveryApi()
+    .AddComposers()
+    .Build();
+
+WebApplication app = builder.Build();
+
+await app.BootUmbracoAsync();
+
+#if (UseHttpsRedirect)
+app.UseHttpsRedirection();
+#endif
+
+app.UseUmbraco()
+    .WithMiddleware(u =>
+    {
+        u.UseBackOffice();
+        u.UseWebsite();
+    })
+    .WithEndpoints(u =>
+    {
+        u.UseBackOfficeEndpoints();
+        u.UseWebsiteEndpoints();
+    });
+
+await app.RunAsync();