Add test for sibling endpoint returning parent id even when its a folder

[Migaroez]

Description

Added a test for the logic introduced in #20083
Updated the GetManagementApiUrl logic to allow for not having to specify the version on the controller/method.

[AndyButland]

Thanks @Migaroez - looks good and can see if verifies the added functionality.

Only concern is that it feels a little odd this being literally the only test for a management API controller. But I guess so long as it's adding value that's OK, and others could be more easily added in future following the pattern.

[AndyButland]

For alignment with the main project, perhaps namespace and folder should be: Umbraco.Cms.Tests.Integration.ManagementApi.Controllers.DocumentType.Trees

[Migaroez]

Only concern is that it feels a little odd this being literally the only test for a management API controller.

Yeah I agree, but it's because the logic there shouldn't be in a controller. When that logic is moved, this test can be moved too and the entrypoint changed while the setup and assert can be more or less the same.

[AndyButland]

Then approving. As you say, maybe it can go away in the future, or it can serve as a basis for other tests on logic in the controllers where it's not straightforward to place or move.