scaleset extensions (#1861)

Co-authored-by: stas <statis@microsoft.com>

src/ApiService/ApiService/Program.cs

@@ -86,6 +86,8 @@ public class Program {
             .AddScoped<IScheduler, Scheduler>()
             .AddScoped<IConfig, Config>()
             .AddScoped<ILogAnalytics, LogAnalytics>()
+            .AddScoped<IExtensions, Extensions>()
+            .AddScoped<IVmssOperations, VmssOperations>()
 
             //Move out expensive resources into separate class, and add those as Singleton
             // ArmClient, Table Client(s), Queue Client(s), HttpClient, etc.\