[DataGrid] Add a SelectColumn Comparer property

[miguelhasse]

Pull Request

📖 Description

Added a SelectColumn comparer property, to allow the use of an IEqualityComparer<> for matching selected row items in scenarios such as Virtual mode rendering, providing a way to compare different item instances representing the same data.

👩‍💻 Reviewer Notes

A working samples can be seen in the following repository projects:

• AdventureWorks showing dynamic data loading using EntityFrameworkAsyncQueryExecutor in a Blazor Server app
• TripPin showing dynamic data loading using ODataAsyncQueryExecutor in a Blazor WebAssembly app

✅ 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