Add Marten end-to-end test using MartenOps

[schnerring]

Add orders/create handler demonstrating MartenOps issue: #426

[jeremydmiller]

@schnerring And this "works on my box". Was this change to the test supposed to fail? If you look at the code generated, it's exactly what it should be doing:

    public class POST_orders_create2 : Wolverine.Http.HttpHandler
    {
        private readonly Wolverine.Http.WolverineHttpOptions _options;
        private readonly Marten.ISessionFactory _sessionFactory;

        public POST_orders_create2(Wolverine.Http.WolverineHttpOptions options, Marten.ISessionFactory sessionFactory) : base(options)
        {
            _options = options;
            _sessionFactory = sessionFactory;
        }



        public override async System.Threading.Tasks.Task Handle(Microsoft.AspNetCore.Http.HttpContext httpContext)
        {
            await using var documentSession = _sessionFactory.OpenSession();
            var (command, jsonContinue) = await ReadJsonAsync<WolverineWebApi.Marten.StartOrder>(httpContext);
            if (jsonContinue == Wolverine.HandlerContinuation.Stop) return;
            (var orderStatus, var startStream) = WolverineWebApi.Marten.MarkItemEndpoint.StartOrder2(command, documentSession);
            
            // Placed by Wolverine's ISideEffect policy
            startStream.Execute(documentSession);

            await WriteJsonAsync(httpContext, orderStatus);

            // Commit the unit of work
            await documentSession.SaveChangesAsync(httpContext.RequestAborted).ConfigureAwait(false);
        }

    }

[schnerring]

When I openend the PR they were failing. I fixed the tests in 0ea4a4b, which with v1.0.1 could probably be reverted.