Improve forms, add helper buttons on add session form

games/static/js/utils.js

@@ -0,0 +1,9 @@
+/**
+ * @description Formats Date to a UTC string accepted by the datetime-local input field.
+ * @param {Date} date
+ * @returns {string}
+ */
+export function toISOUTCString(date) {
+  let month = (date.getMonth() + 1).toString().padStart(2, 0);
+  return `${date.getFullYear()}-${month}-${date.getDate()}T${date.getHours()}:${date.getMinutes()}`;
+}