New backoffice: Use singular name for user and user group controllers (#14121)

* Rename UsersController to UserController

* Rename namespace to User

* Rename UserGroupsControllerBase to UserGroupControllerBase

* Rename namespace to UserGroup

* New backoffice: User and member item endpoints (#14079)

* Implement ByKeys in MemberService

* Implement member item endpoint

* Add routing to static file item controller

* Implement user item endpoint

* Implement user group item endpoint

* return proper response model

* update OpenApi.json

* Add CompatibilitySuppressions

* Cleanup

* Update OpenApi

---------

Co-authored-by: Zeegaan <nge@umbraco.dk>
Co-authored-by: Elitsa <elm@umbraco.dk>

* Make user-group item endpoint singular

* Make user item endpoint singular

* Renamer user and user group folders

* Move from Users namespace to user

* Move from UserGroups namespace to UserGroup

* Update OpenApi.json

* Fix namespace after merge

* Move user item endpoint to singular namespace

* Move user group item endpoint to singular namespace

* Fix open api schema

---------

Co-authored-by: Nikolaj Geisle <70372949+zeegaan@users.noreply.github.com>
Co-authored-by: Zeegaan <nge@umbraco.dk>
Co-authored-by: Elitsa <elm@umbraco.dk>

src/Umbraco.Cms.Api.Management/Controllers/User/DeleteUsersController.cs

@@ -0,0 +1,22 @@
+using Microsoft.AspNetCore.Mvc;
+using Umbraco.Cms.Core.Services;
+using Umbraco.Cms.Core.Services.OperationStatus;
+
+namespace Umbraco.Cms.Api.Management.Controllers.User;
+
+public class DeleteUserController : UserControllerBase
+{
+    public DeleteUserController(IUserService userService) => _userService = userService;
+
+    private readonly IUserService _userService;
+
+    [HttpDelete("{id:guid}")]
+    public async Task<IActionResult> DeleteUser(Guid id)
+    {
+        UserOperationStatus result = await _userService.DeleteAsync(id);
+
+        return result is UserOperationStatus.Success
+            ? Ok()
+            : UserOperationStatusResult(result);
+    }
+}