Use DiagnosticListner for middleware logging

Instead of each middleware having to log that it has started and ended,
the DianosticListner package allows for capturing of these events in a
lightwieght manner.

This commit implements this and removes unncessary logging from most
middleware.

src/Ocelot/Cache/Middleware/OutputCacheMiddleware.cs

@@ -54,8 +54,6 @@ namespace Ocelot.Cache.Middleware
 
             await _next.Invoke(context);
 
-            _logger.LogDebug("succesfully called next middleware");
-
             if (PipelineError)
             {
                 _logger.LogDebug("there was a pipeline error for {downstreamUrlKey}", downstreamUrlKey);