Add timer sample

[lorensr]

Thinking maybe we should add handling workflow cancellation to this sample. Wdyt, and would this be the right way?

namespace TemporalioSamples.Timer;

using Microsoft.Extensions.Logging;
using Temporalio.Workflows;
using System.Threading.Tasks;

[Workflow]
public class MyWorkflow
{
    [WorkflowRun]
    public async Task RunAsync()
    {
        try
        {
            while (true)
            {
                Workflow.CancellationToken.ThrowIfCancellationRequested();

                await Workflow.DelayAsync(1000, Workflow.CancellationToken);

                var result = await Workflow.ExecuteActivityAsync(
                    () => MyActivities.Charge(user),
                    new() { StartToCloseTimeout = TimeSpan.FromMinutes(5) },
                    Workflow.CancellationToken); // Pass the cancellation token

                Workflow.Logger.LogInformation("Activity result: {Result}", result);
            }
        }
        catch (OperationCanceledException)
        {
            // Handle any cleanup upon cancellation here
            Workflow.Logger.LogInformation("Workflow cancelled.");
        }
    }
}

[cretz]

Thinking maybe we should add handling workflow cancellation to this sample. Wdyt, and would this be the right way?

The workflow cancellation token is already the default cancellation token for these calls if none provided so you don't have to change any workflow code.

[cretz]

We haven't on most samples, but we may find using https://github.com/temporalio/sdk-dotnet/tree/main/src/Temporalio.Extensions.Hosting for worker running to be easier in our samples here and elsewhere (this is what many of our users use)

[lorensr]

Making worker file shorter sgtm, going to leave this for future work for time's sake.

[cretz]

OK, can merge. I have opened #59 for finishing out the sample.