Moved logic from FolderTreeControllerBase service layer

[bergmania]

Summary

This PR moves some logic from the FolderTreeControllerBase into the EntityService and EntityRepository.

This required the repository to support multiple orderings statements. To make this part non-breaking, I added a Ordering? Next property on the Ordering class, that is currently only supported by the EntityRepository.

Test

• Ensure the Root / Children endpoints works as expected
  • Folders should be listed before items
  • Sorting by name if type do not allow sorting - E.g. Document Types.
• Ensure take=0 cases works as expected and return the correct count.

[kjac]

The code looks great and the whole thing tests out really well.

✅ Pagination works
✅ Take by zero works

However, I think the custom ordering should have been added to DataTypeTreeControllerBase instead of MediaTypeTreeControllerBase.

Here's what I see in the UI (and in the endpoint outputs too):

Data types:

Media types:

When moving the custom ordering to data types from media types, the folders are correctly placed at the top:

Data types:

Media types:

It kinda also makes sense when considering it's an alphanumeric sorting on NodeObjectType:

• NodeObjectType.DataType: 30A2A501-1978-4DDB-A57B-F7EFED43BA3C
• NodeObjectType.DataTypeContainer: 521231E3-8B37-469C-9F9D-51AFC91FEB7B
• NodeObjectType.MediaType: 4EA4382B-2F5A-4C2B-9587-AE9B3CF3602E
• NodeObjectType.MediaTypeContainer: 42AEF799-B288-4744-9B10-BE144B73CDC4

I'll take the liberty of pushing those changes 😄

[kjac]

Works like a charm!