Improve guidance for .NET Worker Services

[mattjohnsonpint]

Problem Statement

We should provide documentation and samples for integrating Sentry with .NET Worker Services.

Note, we already have the Generic Host sample, but this is slightly different.

Solution Brainstorm

• Build a sample starting from dotnet new worker
• Add Sentry.Extensions.Logging
• Clear the scope before the first execution (requires Add Scope.Clear and Scope.ClearBreadcrumbs #2272)
• Push and dispose a new scope for each inner loop of the worker
• Enable tracing, and start/finish a new transaction for each inner loop of the worker
• Add a new guide to the Sentry .NET docs

[mattjohnsonpint]

Also, explain clearly that global mode should be false for background workers. Update docs for IsGlobalMode.

See https://twitter.com/vekzdran/status/1646886760096362497

[mattjohnsonpint]

POC:

public class Worker : BackgroundService
{
    private readonly IHub _hub;

    public Worker(IHub hub)
    {
        _hub = hub;
    }

    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        while (!stoppingToken.IsCancellationRequested)
        {
            using var _ = _hub.PushScope();
            var transaction = _hub.StartTransaction($"{nameof(Worker)}.{nameof(DoWorkAsync)}", "function");
            try
            {
                _hub.ConfigureScope(scope =>
                {
                    scope.Clear();
                    scope.Transaction = transaction;
                });

                await DoWorkAsync(stoppingToken);
            }
            catch(Exception exception)
            {
                transaction.Finish(exception);
            }
            finally
            {
                transaction.Finish();
            }
        }
    }
}

[mattjohnsonpint]

Updated POC. Requires vNext (3.31.0) for #2303 & #2309.

public class Worker : BackgroundService
{
    private readonly IHub _hub;

    public Worker(IHub hub)
    {
        _hub = hub;
    }

    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        while (!stoppingToken.IsCancellationRequested)
        {
            await _hub.WithScopeAsync(async scope =>
            {
                scope.Clear();

                var transaction = _hub.StartTransaction($"{nameof(Worker)}.{nameof(DoWorkAsync)}", "function");
                scope.Transaction = transaction;

                try
                {
                    await DoWorkAsync(stoppingToken);
                }
                catch (Exception exception)
                {
                    transaction.Finish(exception);
                }
                finally
                {
                    transaction.Finish();
                }
            });
        }
    }
}