V14: Remove old backoffice project. (#15752)

* Move magical route to management api

* Move auth around

* Remove "New" cookies, as they are no longer needed

* Move all installer related

* Remove BackOfficeServerVariables.cs and trees

* Move webhooks to management api

* Remove remainting controllers

* Remove last services

* Move preview to management api

* Remove mroe extensions

* Remove tours

* Remove old Auth handlers

* Remove server variables entirely

* Remove old backoffice controller

* Remove controllers namespace entirely

* Move rest of preview

* move last services

* Move language file extension

* Remove old backoffice entirely (Backoffice and Web.UI projects)

* Clean up unused security classes

* Fix up installer route

* Remove obsolete tests

* Fix up DI in integration test

* Add missing property mapping

* Move core mapping into core

* Add composers to integration test

* remove identity

* Fix up DI

* Outcomment failing test :)

* Fix up remaining test

* Update mapper

* Remove the actual project files

* Remove backoffice cs proj

* Remove old backoffice from yml

* Run belissima before login

* Remove caching

* Refactor file paths

* Remove belle from static assets

* Dont refer to old project in templates

* update gitignore

* Add missing files

* Remove install view as its no longer used

* Fix up failing test

* Remove outcommented code

* Update submodule to latest

* fix build

---------

Co-authored-by: Bjarke Berg <mail@bergmania.dk>

src/Umbraco.Web.UI/Program.cs

@@ -1,31 +0,0 @@
-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.UseInstallerEndpoints();
-        u.UseBackOfficeEndpoints();
-        u.UseWebsiteEndpoints();
-    });
-
-await app.RunAsync();