added IEventSubscriber amd EventDistributorHostedService to optimize event processing

Oqtane.Server/Infrastructure/EventSubscribers/CacheInvalidationEventSubscriber.cs

@@ -0,0 +1,24 @@
+using Microsoft.Extensions.Caching.Memory;
+using Oqtane.Models;
+using Oqtane.Shared;
+
+namespace Oqtane.Infrastructure.EventSubscribers
+{
+    public class CacheInvalidationEventSubscriber : IEventSubscriber
+    {
+        private readonly IMemoryCache _cache;
+
+        public CacheInvalidationEventSubscriber(IMemoryCache cache)
+        {
+            _cache = cache;
+        }
+
+        public void EntityChanged(SyncEvent syncEvent)
+        {
+            if (syncEvent.EntityName == "Site" && syncEvent.Action == SyncEventActions.Refresh)
+            {
+                _cache.Remove($"site:{syncEvent.TenantId}:{syncEvent.EntityId}");
+            }
+        }
+    }
+}