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

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

src/Umbraco.Web.UI.New/Views/_ViewImports.cshtml

@@ -0,0 +1,8 @@
+@using Umbraco.Extensions
+@using Umbraco.Cms.Web.Common.PublishedModels
+@using Umbraco.Cms.Web.Common.Views
+@using Umbraco.Cms.Core.Models.PublishedContent
+@using Microsoft.AspNetCore.Html
+@addTagHelper *, Microsoft.AspNetCore.Mvc.TagHelpers
+@addTagHelper *, Smidge
+@inject Smidge.SmidgeHelper SmidgeHelper