optimize client assembly download service, add support for site level scripts

Oqtane.Server/Infrastructure/ServerState.cs

@@ -0,0 +1,12 @@
+using System.Collections.Generic;
+using Oqtane.Models;
+
+namespace Oqtane.Infrastructure
+{
+    public class ServerState
+    {
+        public int SiteId { get; set; }
+        public List<string> Assemblies { get; set; } = new List<string>();
+        public List<Resource>Scripts { get; set; } = new List<Resource>();
+    }
+}