Logging for ga (#698)

Adding a robustness change to call close on logger before process exit.
Also adding a designer.cs file needed by a script csproj that got missed out in previous checkin due to .gitignore entry.

src/Microsoft.SqlTools.Credentials/Program.cs

@@ -62,6 +62,10 @@ namespace Microsoft.SqlTools.Credentials
                 Logger.WriteWithCallstack(TraceEventType.Critical, $"An unhandled exception occurred: {e}");
                 Environment.Exit(1);
             }
+            finally
+            {
+                Logger.Close();
+            }
         }
     }
 }