IO-952 add confirm to bill enter with discrepancy.

client/src/utils/asyncConfirm.js

@@ -0,0 +1,9 @@
+function confirmDialog(msg) {
+  return new Promise(function (resolve, reject) {
+    let confirmed = window.confirm(msg);
+
+    return confirmed ? resolve(true) : resolve(false);
+  });
+}
+
+export default confirmDialog;