[DataGrid] Add IGridSort interface, fixes sorting when using ItemsProvider

[StevenRasmussen]

Fixes #3290

Before writing unit tests etc... I wanted to get feedback on whether this would be an acceptable approach.

Pull Request

📖 Description

🎫 Issues

👩‍💻 Reviewer Notes

📑 Test Plan

✅ Checklist

General

• I have added tests for my changes.
• I have tested my changes.
• I have updated the project documentation to reflect my changes.
• I have read the CONTRIBUTING documentation and followed the standards for this project.

Component-specific

• I have added a new component
• I have added Unit Tests for my new component
• I have modified an existing component
• I have validated the Unit Tests for an existing component

⏭ Next Steps

[vnbaaij]

Apart from the namespace name and whitespace remarks, think this looks quite good already. 👍

I don't understand the StaticGridSort purpose. Is it the default IGridSort that gets applied. I don't see it called anywhere (yet?). If it is indeed the default, than I'd suggest to name it like that as well DefaultGridSort

[StevenRasmussen]

@vnbaaij - Thanks for the feedback! It was late last night when I created this and so I was struggling to come up with a good name for the new class. I'm still not certain that ColumnKeyGridSort is the best... but I do think it more closely represents its purpose now. I've added a demo page and so you can see it in action and what problem it is solving. Unless you need anything else I think the PR should be ready for merging. Thanks!

[davhdavh]

Very nice way of solving the issue