ColumnTypeSelector for better column autogeneration control

[Algorithman]

I wrote a column type selector for autogeneration control: https://github.com/Algorithman/Avalonia.Controls.DataGrid/tree/columnTypeSelector

Can be used in xaml or in code and gives full control over which column type should be used based on property name and data type or data type alone.

If you're interested in extensions like this, give me a holler, then I'll submit a PR for this (and more).