[Bug Report]: Web UI is trying to handle resources that do not belong to it

Prerequisites

• [X] I have searched issues to ensure it has not already been reported

Description

When performing an HTTP request to another middleware (in this case, it happened requesting to a resource owned by the KafkaFlow middleware), the Rules.Framework Web UI tries to handle it and fails with an exception.

Steps to reproduce

1. Register Web UI middleware.
2. Register other middlewares after.
3. Run the app.
4. Perform a request that is supposed to be handled by other middleware.

Expected behavior

The Web UI should not try to handle resources that are not its' responsibility.

Actual behavior

When trying to access another resource that does not belong to Rules.Framework Web UI (from KafkaFlow UI in this case), an exception is thrown:

    System.InvalidOperationException: StatusCode cannot be set because the response has already started.
       at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http.HttpProtocol.ThrowResponseAlreadyStartedException(String value)
       at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http.HttpProtocol.Microsoft.AspNetCore.Http.Features.IHttpResponseFeature.set_StatusCode(Int32 value)
       at KafkaFlow.Admin.Dashboard.ApplicationBuilderExtensions.<>c__DisplayClass1_2.<<UseKafkaFlowDashboard>b__11>d.MoveNext()
    --- End of stack trace from previous location ---
       at Microsoft.AspNetCore.Routing.EndpointMiddleware.<Invoke>g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger)
       at Microsoft.AspNetCore.Builder.Extensions.MapMiddleware.InvokeCore(HttpContext context, String matchedPath, String remainingPath)
       at Rules.Framework.WebUI.WebUIMiddleware.InvokeAsync(HttpContext httpContext)
       at Microsoft.AspNetCore.Builder.RouterMiddleware.Invoke(HttpContext httpContext)
       at Swashbuckle.AspNetCore.SwaggerUI.SwaggerUIMiddleware.Invoke(HttpContext httpContext)
       at Swashbuckle.AspNetCore.Swagger.SwaggerMiddleware.Invoke(HttpContext httpContext, ISwaggerProvider swaggerProvider)
       at Farfetch.Framework.PingPong.AspNetCore.PingPongMiddleware.Invoke(HttpContext httpContext)
       at Farfetch.Framework.PingPong.AspNetCore.PingPongMiddleware.Invoke(HttpContext httpContext)
       at Farfetch.Framework.PingPong.AspNetCore.PingPongMiddleware.Invoke(HttpContext httpContext)
       at Prometheus.HttpMetrics.HttpInProgressMiddleware.Invoke(HttpContext context)
       at Farfetch.Framework.Monitoring.WebMetrics.AspNetCore.Middlewares.HttpRequestDurationMiddleware.Invoke(HttpContext context)
       at Farfetch.Framework.Monitoring.WebMetrics.AspNetCore.Middlewares.HttpRequestCountMiddleware.Invoke(HttpContext context)
       at NewRelic.Providers.Wrapper.AspNetCore.WrapPipelineMiddleware.Invoke(HttpContext context)

Rules Framework version

2.0.2

Proposed solution:

1. Move the handling of the next middleware to InvokeAsync.
2. Add an additional filter resource segment to StaticFileMiddleware configuration.

private async Task<bool> ExecuteHandlersAsync(HttpContext httpContext)
{
    var results = this.httpRequestHandlers.Select(d => d
          .HandleAsync(httpContext.Request, httpContext.Response, this.next));

    var handle = await Task.WhenAll(results).ConfigureAwait(false);
    return handle.All(d => !d);
}

public async Task InvokeAsync(HttpContext httpContext)
{
    var anyHandlerExecuted = await this.ExecuteHandlersAsync(httpContext).ConfigureAwait(false);
    if (!anyHandlerExecuted)
    {
        await this.next(httpContext).ConfigureAwait(false);
        if (!httpContext.Response.HasStarted)
        {
            await this.ExecuteStaticFileMiddlewareAsync(httpContext).ConfigureAwait(true);
        }
    }
}

We can change the StaticFileMiddleware configuration like this:

var staticFileOptions = new StaticFileOptions
{
    RequestPath = string.IsNullOrEmpty(options.RoutePrefix) ? "/rules-static" : $"/{options.RoutePrefix}/rules-static",
    FileProvider = provider,
    ServeUnknownFileTypes = true
};

But we have to check other files in the Web UI that are using static files and include the /rules-static resource segment.