Convention-Based Receiver Middleware Extensions

[tsutomi]

The current set of ASP.NET Core receivers allows two different types of webhook handlers:

1. Handlers registered as services and resolved by a factory/based middleware, that does not accept parameters
2. Handlers defined directly in the convention-based middleware as callbacks

We should extend the design to have a convention-based middleware that receive handlers from dependency injection and accepts arguments to configure its execution

Example:

public class Program {
    public void ConfigureServices(IServiceCollection services) {
        services.AddWebhookReceiver<MyWebhook>()
            .AddHandler<MyHandler>();
    }

    public void Configure(IApplicationBuilder app) {
        app.UseWebhookReceiver<MyWebhook>("/webhooks" new WebhookReceiverOptions {
        });
    }
}