Added first app template

backend/login-counter/app.CredentialManager/Base64.cs

@@ -0,0 +1,25 @@
+using System;
+
+namespace app.CredentialManager
+{
+    public static class Base64
+    {   
+        public static string Encode(string credentials)
+        {
+            var plainTextBytes = System.Text.Encoding.UTF8.GetBytes(credentials);
+            return System.Convert.ToBase64String(plainTextBytes);
+        }
+
+        public static string Decode(string credentials)
+        {
+            var base64EncodedBytes = System.Convert.FromBase64String(credentials);
+            return System.Text.Encoding.UTF8.GetString(base64EncodedBytes);
+        }
+
+        public static string DecodeConnectionString(string connectionString, string credentials)
+        {
+            string decodedCredentials = Decode(credentials);
+            return connectionString += $"password={decodedCredentials};";
+        }
+    }
+}