Convert throw and thread helpers to UCO

[am11]

Contributes to prio3 from #123864

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[am11]

@EgorBot -osx_arm64

using System;
using BenchmarkDotNet.Attributes;
using BenchmarkDotNet.Running;

BenchmarkSwitcher
    .FromAssembly(typeof(ExceptionBench).Assembly)
    .Run(args);

[MemoryDiagnoser]
[SimpleJob(warmupCount: 3, iterationCount: 10)]
public class ExceptionBench
{
    private static volatile int _sink;

    [Benchmark]
    public void ThrowCatch()
    {
        try
        {
            Thrower();
        }
        catch (InvalidOperationException ex)
        {
            _sink = ex.HResult;
        }
    }

    private static void Thrower()
    {
        throw new InvalidOperationException("boom");
    }

    [Benchmark]
    public void NullRefThrow()
    {
        try
        {
            object o = null!;
            _ = o.ToString(); // NullRef
        }
        catch
        {
        }
    }

    [Benchmark]
    public void Rethrow()
    {
        try
        {
            try
            {
                Thrower();
            }
            catch
            {
                throw;
            }
        }
        catch
        {
        }
    }
}

[jkotas]

I would split Start and Finalizer into a separate PR to make this easier to land.

[jkotas]

This one and Thread.Start have concerns about unhandled exception post-mortem diagnostics, similar to the concerns we had with Main method. We need to make sure that the unhandled exceptions produce crash dump with the original stack preserved for good post-mortem diagnostics, on both Windows and Unix. It does not seem to be the case by just looking at the code.

(Unlike the Main method, we do not need to hide the extra frames from stacktraces in these cases.)

[am11]

Updated accordingly (without conditioning stacktrace). I am waiting for the CI run to understand if we need to further fine-tune it.

[janvorli]

These changes in the ExceptionHandling.cs are not needed. Managed exception is never propagated out of the RhThrowEx et al.