Check Runner Zip Hash on Upgrade (#967)

* Check Hash if it exists on runner update

src/Sdk/Common/Common/Utility/HashAlgorithmExtensions.cs

@@ -0,0 +1,27 @@
+using System.IO;
+using System.Security.Cryptography;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace GitHub.Services.Common
+{
+    public static class HashAlgorithmExtensions
+    {
+        public static async Task<byte[]> ComputeHashAsync(this HashAlgorithm hashAlg, Stream inputStream)
+        {
+            byte[] buffer = new byte[4096];
+
+            while (true)
+            {
+                int read = await inputStream.ReadAsync(buffer, 0, buffer.Length);
+                if (read == 0)
+                    break;
+
+                hashAlg.TransformBlock(buffer, 0, read, null, 0);
+            }
+
+            hashAlg.TransformFinalBlock(buffer, 0, 0);
+            return hashAlg.Hash;
+        }
+    }
+}

src/Sdk/Common/Common/Utility/PrimitiveExtensions.cs

@@ -85,5 +85,19 @@ namespace GitHub.Services.Common
             var bytes = FromBase64StringNoPadding(base64String);
             return BitConverter.ToString(bytes).Replace("-", String.Empty);
         }
+
+        /// <summary>
+        /// Converts byte array into a hex string
+        /// </summary>
+        public static String ConvertToHexString(byte[] bytes)
+        {
+            // Convert byte array to string
+            var sBuilder = new StringBuilder();
+            for (int i = 0; i < bytes.Length; i++)
+            {
+                sBuilder.Append(bytes[i].ToString("x2"));
+            }
+            return sBuilder.ToString();
+        }
     }
 }