Fixing GetServerSystemInfo for Azure DBs (#1231)

* Not throwing errors when we try to fetch SQL server properties like server count and physical mem.

* Fixed comment

* Renaming get server cpu count

* Adding more detailed comment over here

* Making properties cpu count and physical memory to nullable<int> so they are defaulted to null.

* Fixing rest of the properties to nullable.

src/Microsoft.SqlTools.ServiceLayer/Connection/Contracts/ServerInfo.cs

@@ -3,6 +3,7 @@
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
 //
 
+using System;
 using System.Collections.Generic;
 
 namespace Microsoft.SqlTools.ServiceLayer.Connection.Contracts
@@ -70,12 +71,12 @@ namespace Microsoft.SqlTools.ServiceLayer.Connection.Contracts
         /// <summary>
         /// The CPU count of the host running the server.
         /// </summary>
-        public int CpuCount;
+        public Nullable<int> CpuCount;
 
         /// <summary>
         /// The physical memory of the host running the server in MBs.
         /// </summary>
-        public int PhysicalMemoryInMB;
+        public Nullable<int> PhysicalMemoryInMB;
 
         /// <summary>
         /// Server options