DebuggerTypeProxy and DebuggerDisplay for types you don't own

Add DebuggerTypeProxy and DebuggerDisplay attributes on assembly level to take control over what is displayed in the debugger, even for types that you don’t own.

using System.Diagnostics;
using System.Xml.Linq;

[assembly: DebuggerDisplay("XML: {this.ToString(SaveOptions.None),nq}", Target=typeof(XDocument))]
[assembly: DebuggerTypeProxy(typeof(ConsoleApp.XElementDebuggerTypeProxy), Target=typeof(XElement))]

namespace ConsoleApp;

class Program
{
    static void Main(string[] args)
    {
        var xml = """
            <person>
                <firstName>Donald</firstName>
                <lastName>Duck</lastName>
            </person>
            """;
            
        var xDoc = XDocument.Parse(xml);
        var element = new XElement("city", new XText("Duckburg"));
        xDoc.Root!.Add(element);

        Console.WriteLine(xDoc);
    }
}

public class XElementDebuggerTypeProxy
{
    private readonly XElement _xElement;
    public string Xml => $"{nameof(XElement)}: {_xElement.ToString(SaveOptions.None)}";
    public XElementDebuggerTypeProxy(XElement xElement) =>
        _xElement = xElement;
}